diff --git a/README.rst b/README.rst
index 83085bf..9df34f7 100644
--- a/README.rst
+++ b/README.rst
@@ -161,7 +161,7 @@ Extract property of data for each data from a matrix
     ---------- str_len ----------
     [1, 3, 2, 1, 1, 4, 3, 3, 19]
     [1, 3, 3, 3, 3, 5, 3, 3, 19]
-    [1, 4, 4, 2, 3, 4, 3, 3, 25]
+    [1, 4, 4, 2, 3, 4, 3, 3, 24]
 
     ---------- integer_digits ----------
     [1, 1, nan, 1, 1, nan, nan, nan, nan]
@@ -218,10 +218,10 @@ Extract property of data for each column from a matrix
     [right, right, left, right, left, left, left, left, left]
 
     ---------- padding_len ----------
-    [3, 5, 4, 3, 3, 5, 3, 3, 25]
+    [3, 5, 4, 4, 3, 5, 3, 3, 24]
 
     ---------- decimal_places ----------
-    [nan, 2, nan, 1, 1, nan, nan, nan, nan]
+    [0, 2, nan, 1, 1, nan, nan, nan, nan]
 
 
 Dependencies
diff --git a/dataproperty/__init__.py b/dataproperty/__init__.py
index 9565b24..0b2e9bc 100644
--- a/dataproperty/__init__.py
+++ b/dataproperty/__init__.py
@@ -11,7 +11,7 @@
 from ._align import Align
 from ._align_getter import align_getter
 from ._container import MinMaxContainer
-from ._typecode import Typecode
+from .type import Typecode
 
 from ._data_property import ColumnDataProperty
 from ._data_property import DataProperty
diff --git a/dataproperty/_align_getter.py b/dataproperty/_align_getter.py
index 69f33d6..5a7d081 100644
--- a/dataproperty/_align_getter.py
+++ b/dataproperty/_align_getter.py
@@ -7,7 +7,7 @@
 from __future__ import absolute_import
 
 from ._align import Align
-from ._typecode import Typecode
+from .type import Typecode
 
 
 class AlignGetter(object):
diff --git a/dataproperty/_data_property.py b/dataproperty/_data_property.py
index 90e92b5..ce28432 100644
--- a/dataproperty/_data_property.py
+++ b/dataproperty/_data_property.py
@@ -11,8 +11,8 @@
 from ._container import MinMaxContainer
 from ._error import TypeConversionError
 from ._interface import DataPeropertyInterface
-from ._typecode import Typecode
-from ._type_checker import FloatTypeChecker
+from .type import Typecode
+from .type import FloatTypeChecker
 
 from ._function import is_nan
 from ._function import get_number_of_digit
diff --git a/dataproperty/_factory.py b/dataproperty/_factory.py
index 66169be..6176f69 100644
--- a/dataproperty/_factory.py
+++ b/dataproperty/_factory.py
@@ -15,14 +15,14 @@
 from .converter import FloatConverterCreator
 from .converter import BoolConverterCreator
 from .converter import DateTimeConverterCreator
-from ._type_checker_creator import NoneTypeCheckerCreator
-from ._type_checker_creator import StringTypeCheckerCreator
-from ._type_checker_creator import IntegerTypeCheckerCreator
-from ._type_checker_creator import FloatTypeCheckerCreator
-from ._type_checker_creator import BoolTypeCheckerCreator
-from ._type_checker_creator import DateTimeTypeCheckerCreator
-from ._type_checker_creator import InfinityCheckerCreator
-from ._type_checker_creator import NanCheckerCreator
+from .type import NoneTypeCheckerCreator
+from .type import StringTypeCheckerCreator
+from .type import IntegerTypeCheckerCreator
+from .type import FloatTypeCheckerCreator
+from .type import BoolTypeCheckerCreator
+from .type import DateTimeTypeCheckerCreator
+from .type import InfinityCheckerCreator
+from .type import NanCheckerCreator
 
 
 @six.add_metaclass(abc.ABCMeta)
diff --git a/dataproperty/_function.py b/dataproperty/_function.py
index 47c3571..b098434 100644
--- a/dataproperty/_function.py
+++ b/dataproperty/_function.py
@@ -16,7 +16,7 @@ def is_integer(value):
         Use IntegerTypeChecker class instead of this function.
     """
 
-    from ._type_checker import IntegerTypeChecker
+    from .type import IntegerTypeChecker
 
     return IntegerTypeChecker(value).is_type()
 
@@ -38,7 +38,7 @@ def is_float(value):
         Use FloatTypeChecker class instead of this function.
     """
 
-    from ._type_checker import FloatTypeChecker
+    from .type import FloatTypeChecker
 
     return FloatTypeChecker(value).is_type()
 
@@ -97,7 +97,7 @@ def is_datetime(value):
 
 
 def get_integer_digit(value):
-    from ._type_checker import FloatTypeChecker
+    from .type import FloatTypeChecker
 
     abs_value = abs(float(value))
 
@@ -114,7 +114,7 @@ def get_integer_digit(value):
 def _get_decimal_places(value, integer_digits):
     from collections import namedtuple
     from six.moves import range
-    from ._type_checker import IntegerTypeChecker
+    from .type import IntegerTypeChecker
 
     float_digit_len = 0
     if IntegerTypeChecker(value).is_type():
diff --git a/dataproperty/_interface.py b/dataproperty/_interface.py
index dfbec08..71002bd 100644
--- a/dataproperty/_interface.py
+++ b/dataproperty/_interface.py
@@ -10,7 +10,7 @@
 import six
 
 from ._function import is_nan
-from ._typecode import Typecode
+from .type import Typecode
 
 
 @six.add_metaclass(abc.ABCMeta)
diff --git a/dataproperty/type/__init__.py b/dataproperty/type/__init__.py
new file mode 100644
index 0000000..30049c2
--- /dev/null
+++ b/dataproperty/type/__init__.py
@@ -0,0 +1,27 @@
+# encoding: utf-8
+
+"""
+.. codeauthor:: Tsuyoshi Hombashi <gogogo.vm@gmail.com>
+"""
+
+from __future__ import absolute_import
+
+from ._checker import NoneTypeChecker
+from ._checker import StringTypeChecker
+from ._checker import IntegerTypeChecker
+from ._checker import FloatTypeChecker
+from ._checker import BoolTypeChecker
+from ._checker import DateTimeTypeChecker
+from ._checker import InfinityChecker
+from ._checker import NanChecker
+
+from ._checker_creator import NoneTypeCheckerCreator
+from ._checker_creator import StringTypeCheckerCreator
+from ._checker_creator import IntegerTypeCheckerCreator
+from ._checker_creator import FloatTypeCheckerCreator
+from ._checker_creator import BoolTypeCheckerCreator
+from ._checker_creator import DateTimeTypeCheckerCreator
+from ._checker_creator import InfinityCheckerCreator
+from ._checker_creator import NanCheckerCreator
+
+from ._typecode import Typecode
diff --git a/dataproperty/_type_checker.py b/dataproperty/type/_checker.py
similarity index 92%
rename from dataproperty/_type_checker.py
rename to dataproperty/type/_checker.py
index 5eae3a4..fbcef79 100644
--- a/dataproperty/_type_checker.py
+++ b/dataproperty/type/_checker.py
@@ -10,14 +10,14 @@
 
 import six
 
-from .converter import NopConverterCreator
-from .converter import StringConverterCreator
-from .converter import IntegerConverterCreator
-from .converter import FloatConverterCreator
-from .converter import BoolConverterCreator
-from .converter import DateTimeConverterCreator
-from ._error import TypeConversionError
-from ._function import is_nan
+from ..converter import NopConverterCreator
+from ..converter import StringConverterCreator
+from ..converter import IntegerConverterCreator
+from ..converter import FloatConverterCreator
+from ..converter import BoolConverterCreator
+from ..converter import DateTimeConverterCreator
+from .._error import TypeConversionError
+from .._function import is_nan
 from ._typecode import Typecode
 
 
diff --git a/dataproperty/_type_checker_creator.py b/dataproperty/type/_checker_creator.py
similarity index 81%
rename from dataproperty/_type_checker_creator.py
rename to dataproperty/type/_checker_creator.py
index 5e50f16..13dc52b 100644
--- a/dataproperty/_type_checker_creator.py
+++ b/dataproperty/type/_checker_creator.py
@@ -9,14 +9,14 @@
 
 import six
 
-from ._type_checker import NoneTypeChecker
-from ._type_checker import StringTypeChecker
-from ._type_checker import IntegerTypeChecker
-from ._type_checker import FloatTypeChecker
-from ._type_checker import BoolTypeChecker
-from ._type_checker import DateTimeTypeChecker
-from ._type_checker import InfinityChecker
-from ._type_checker import NanChecker
+from ._checker import NoneTypeChecker
+from ._checker import StringTypeChecker
+from ._checker import IntegerTypeChecker
+from ._checker import FloatTypeChecker
+from ._checker import BoolTypeChecker
+from ._checker import DateTimeTypeChecker
+from ._checker import InfinityChecker
+from ._checker import NanChecker
 
 
 @six.add_metaclass(abc.ABCMeta)
diff --git a/dataproperty/_typecode.py b/dataproperty/type/_typecode.py
similarity index 100%
rename from dataproperty/_typecode.py
rename to dataproperty/type/_typecode.py
diff --git a/ipynb/DataProperty.ipynb b/ipynb/DataProperty.ipynb
index 168de04..4f9eca7 100644
--- a/ipynb/DataProperty.ipynb
+++ b/ipynb/DataProperty.ipynb
@@ -123,7 +123,7 @@
     {
      "data": {
       "text/plain": [
-       "data=2017-01-01 01:23:45+09:00, typename=DATETIME, align=left, str_len=25, integer_digits=nan, decimal_places=nan, additional_format_len=0"
+       "data=2017-01-01 01:23:45+09:00, typename=DATETIME, align=left, str_len=24, integer_digits=nan, decimal_places=nan, additional_format_len=0"
       ]
      },
      "execution_count": 6,
@@ -187,7 +187,7 @@
       "---------- str_len ----------\n",
       "[1, 3, 2, 1, 1, 4, 3, 3, 19]\n",
       "[1, 3, 3, 3, 3, 5, 3, 3, 19]\n",
-      "[1, 4, 4, 2, 3, 4, 3, 3, 25]\n",
+      "[1, 4, 4, 2, 3, 4, 3, 3, 24]\n",
       "\n",
       "---------- integer_digits ----------\n",
       "[1, 1, nan, 1, 1, nan, nan, nan, nan]\n",
@@ -241,10 +241,10 @@
       "[right, right, left, right, left, left, left, left, left]\n",
       "\n",
       "---------- padding_len ----------\n",
-      "[3, 5, 4, 3, 3, 5, 3, 3, 25]\n",
+      "[3, 5, 4, 4, 3, 5, 3, 3, 24]\n",
       "\n",
       "---------- decimal_places ----------\n",
-      "[nan, 2, nan, 1, 1, nan, nan, nan, nan]\n"
+      "[0, 2, nan, 1, 1, nan, nan, nan, nan]\n"
      ]
     }
    ],
@@ -305,7 +305,7 @@
       "row=2, col=5: data=True, typename=BOOL, align=left, str_len=4, integer_digits=nan, decimal_places=nan, additional_format_len=0\n",
       "row=2, col=6: data=inf, typename=INFINITY, align=left, str_len=3, integer_digits=nan, decimal_places=nan, additional_format_len=0\n",
       "row=2, col=7: data=nan, typename=NAN, align=left, str_len=3, integer_digits=nan, decimal_places=nan, additional_format_len=0\n",
-      "row=2, col=8: data=2017-01-01 01:23:45+09:00, typename=DATETIME, align=left, str_len=25, integer_digits=nan, decimal_places=nan, additional_format_len=0\n"
+      "row=2, col=8: data=2017-01-01 01:23:45+09:00, typename=DATETIME, align=left, str_len=24, integer_digits=nan, decimal_places=nan, additional_format_len=0\n"
      ]
     }
    ],
@@ -329,15 +329,15 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "col=0: typename=INT, align=right, padding_len=3, integer_digits=(min=1, max=1), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n",
+      "col=0: typename=INT, align=right, padding_len=3, integer_digits=(min=1, max=1), decimal_places=(min=0, max=0), additional_format_len=(min=0, max=0)\n",
       "col=1: typename=FLOAT, align=right, padding_len=5, integer_digits=(min=1, max=1), decimal_places=(min=1, max=2), additional_format_len=(min=0, max=0)\n",
       "col=2: typename=STRING, align=left, padding_len=4, integer_digits=(min=None, max=None), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n",
-      "col=3: typename=FLOAT, align=right, padding_len=3, integer_digits=(min=1, max=1), decimal_places=(min=1, max=1), additional_format_len=(min=0, max=1)\n",
-      "col=4: typename=STRING, align=left, padding_len=3, integer_digits=(min=1, max=1), decimal_places=(min=1, max=1), additional_format_len=(min=0, max=0)\n",
+      "col=3: typename=FLOAT, align=right, padding_len=4, integer_digits=(min=1, max=1), decimal_places=(min=0, max=1), additional_format_len=(min=0, max=1)\n",
+      "col=4: typename=STRING, align=left, padding_len=3, integer_digits=(min=1, max=1), decimal_places=(min=0, max=1), additional_format_len=(min=0, max=0)\n",
       "col=5: typename=BOOL, align=left, padding_len=5, integer_digits=(min=None, max=None), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n",
       "col=6: typename=INFINITY, align=left, padding_len=3, integer_digits=(min=None, max=None), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n",
       "col=7: typename=NAN, align=left, padding_len=3, integer_digits=(min=None, max=None), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n",
-      "col=8: typename=DATETIME, align=left, padding_len=25, integer_digits=(min=None, max=None), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n"
+      "col=8: typename=DATETIME, align=left, padding_len=24, integer_digits=(min=None, max=None), decimal_places=(min=None, max=None), additional_format_len=(min=0, max=0)\n"
      ]
     }
    ],
@@ -377,7 +377,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.5.1"
+   "version": "3.5.2"
   }
  },
  "nbformat": 4,
diff --git a/test/test_type_checker.py b/test/test_type_checker.py
index cb00eec..d211dbd 100644
--- a/test/test_type_checker.py
+++ b/test/test_type_checker.py
@@ -12,7 +12,7 @@
 import pytest
 import six
 
-import dataproperty._type_checker as tc
+import dataproperty.type as tc
 from dataproperty import Typecode
 from decimal import Decimal
 
diff --git a/test/test_type_checker_creator.py b/test/test_type_checker_creator.py
index 0596f40..0ad9a6c 100644
--- a/test/test_type_checker_creator.py
+++ b/test/test_type_checker_creator.py
@@ -8,21 +8,20 @@
 
 import pytest
 
-import dataproperty._type_checker_creator as tcc
-import dataproperty._type_checker as tc
+import dataproperty.type as tc
 
 
 class Test_TypeCheckerCreator(object):
 
     @pytest.mark.parametrize(["value", "is_convert", "expected"], [
-        [tcc.NoneTypeCheckerCreator, True, tc.NoneTypeChecker],
-        [tcc.NoneTypeCheckerCreator, False, tc.NoneTypeChecker],
-        [tcc.IntegerTypeCheckerCreator, True, tc.IntegerTypeChecker],
-        [tcc.IntegerTypeCheckerCreator, False, tc.IntegerTypeChecker],
-        [tcc.FloatTypeCheckerCreator, True, tc.FloatTypeChecker],
-        [tcc.FloatTypeCheckerCreator, False, tc.FloatTypeChecker],
-        [tcc.DateTimeTypeCheckerCreator, True, tc.DateTimeTypeChecker],
-        [tcc.DateTimeTypeCheckerCreator, False, tc.DateTimeTypeChecker],
+        [tc.NoneTypeCheckerCreator, True, tc.NoneTypeChecker],
+        [tc.NoneTypeCheckerCreator, False, tc.NoneTypeChecker],
+        [tc.IntegerTypeCheckerCreator, True, tc.IntegerTypeChecker],
+        [tc.IntegerTypeCheckerCreator, False, tc.IntegerTypeChecker],
+        [tc.FloatTypeCheckerCreator, True, tc.FloatTypeChecker],
+        [tc.FloatTypeCheckerCreator, False, tc.FloatTypeChecker],
+        [tc.DateTimeTypeCheckerCreator, True, tc.DateTimeTypeChecker],
+        [tc.DateTimeTypeCheckerCreator, False, tc.DateTimeTypeChecker],
     ])
     def test_normal(self, value, is_convert, expected):
         creator = value()