diff --git a/src/Collection.php b/src/Collection.php
index e6413cb..26b7b35 100644
--- a/src/Collection.php
+++ b/src/Collection.php
@@ -10,6 +10,7 @@
 
 namespace Citrus;
 
+use Citrus\Collection\Fetcher;
 use Citrus\Collection\Filter;
 use Citrus\Collection\Generator;
 use Citrus\Collection\JudgeMentor;
@@ -36,6 +37,32 @@ public function __construct(array $source)
         $this->source = $source;
     }
 
+    /**************************************************************************
+     * Fetcher
+     **************************************************************************/
+
+    /**
+     * 先頭の要素を取得
+     *
+     * @param callable|null $callable
+     * @return mixed
+     */
+    public function first(callable|null $callable = null): mixed
+    {
+        return Fetcher::first($this->source, $callable);
+    }
+
+    /**
+     * 最後の要素を取得
+     *
+     * @param callable|null $callable
+     * @return mixed
+     */
+    public function last(callable|null $callable = null): mixed
+    {
+        return Fetcher::last($this->source, $callable);
+    }
+
     /**************************************************************************
      * Filter
      **************************************************************************/
@@ -389,18 +416,4 @@ public function toKeys(): array
     {
         return array_keys($this->source);
     }
-
-    /**
-     * 一件取得
-     *
-     * @return mixed|null
-     */
-    public function one(): mixed
-    {
-        foreach ($this->source as $one)
-        {
-            return $one;
-        }
-        return null;
-    }
 }
diff --git a/src/Collection/Fetcher.php b/src/Collection/Fetcher.php
new file mode 100644
index 0000000..e850cf9
--- /dev/null
+++ b/src/Collection/Fetcher.php
@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright   Copyright 2020, CitrusCollection. All Rights Reserved.
+ * @author      take64 <take64@citrus.tk>
+ * @license     http://www.citrus.tk/
+ */
+
+namespace Citrus\Collection;
+
+/**
+ * コレクションメソッド(取得系)
+ */
+class Fetcher
+{
+    /**
+     * 先頭の要素を取得
+     *
+     * @param array         $source
+     * @param callable|null $callable function($value, $key)
+     * @return mixed
+     */
+    public static function first(array $source, callable|null $callable = null): mixed
+    {
+        $filtered = Filter::filter($source, $callable);
+        $count = Measurer::count($filtered);
+        // 無ければnull
+        if ($count === 0)
+        {
+            return null;
+        }
+        return array_values($filtered)[0];
+    }
+
+    /**
+     * 最後の要素を取得
+     *
+     * @param array         $source
+     * @param callable|null $callable function($value, $key)
+     * @return mixed
+     */
+    public static function last(array $source, callable|null $callable = null): mixed
+    {
+        $filtered = Filter::filter($source, $callable);
+        $count = Measurer::count($filtered);
+        // 無ければnull
+        if ($count === 0)
+        {
+            return null;
+        }
+        return array_values($filtered)[$count - 1];
+    }
+}
diff --git a/src/Collection/Filter.php b/src/Collection/Filter.php
index ef676fb..37f1d91 100644
--- a/src/Collection/Filter.php
+++ b/src/Collection/Filter.php
@@ -18,12 +18,18 @@ class Filter
     /**
      * callable関数の返却値がtrueの場合に積んで返却する
      *
-     * @param array    $source
-     * @param callable $callable function($value, $key)
+     * @param array         $source
+     * @param callable|null $callable function($value, $key)
      * @return array
      */
-    public static function filter(array $source, callable $callable): array
+    public static function filter(array $source, callable|null $callable = null): array
     {
+        // 無ければそのまま返す
+        if (is_null($callable))
+        {
+            return $source;
+        }
+
         $results = [];
         foreach ($source as $ky => $vl)
         {
diff --git a/src/Collection/Measurer.php b/src/Collection/Measurer.php
index 7d28a9d..00de483 100644
--- a/src/Collection/Measurer.php
+++ b/src/Collection/Measurer.php
@@ -22,7 +22,7 @@ class Measurer
      * @param callable|null $callable function($value, $key)
      * @return int
      */
-    public static function count(array $source, callable|null $callable): int
+    public static function count(array $source, callable|null $callable = null): int
     {
         if (!is_null($callable))
         {
diff --git a/tests/CollectionTest.php b/tests/CollectionTest.php
index 1bb5a77..a837733 100644
--- a/tests/CollectionTest.php
+++ b/tests/CollectionTest.php
@@ -549,17 +549,6 @@ public function sortByProps_ソートした配列を生成して返却()
         ])->toList());
     }
 
-    /**
-     * @test
-     */
-    public function one_一件だけ取得()
-    {
-        // 降順にソート
-        $expected = ['name' => 'a', 'age' => 16];
-        // 検算
-        $this->assertSame($expected, Collection::stream($this->values)->one());
-    }
-
     /**
      * @test
      */
@@ -606,6 +595,32 @@ public function isNotEmpty_要素が空ではない()
             return $value['age'] > 19;
         }));
     }
+
+    /**
+     * @test
+     */
+    public function first_先頭一件取得()
+    {
+        // 検算
+        $this->assertSame($this->values[0], Collection::stream($this->values)->first());
+        // 検算：フィルター
+        $this->assertSame($this->values[1], Collection::stream($this->values)->first(function ($value, $key) {
+            return $value['age'] === 11 or $value['age'] === 13;
+        }));
+    }
+
+    /**
+     * @test
+     */
+    public function last_最後一件取得()
+    {
+        // 検算
+        $this->assertSame($this->values[count($this->values) - 1], Collection::stream($this->values)->last());
+        // 検算：フィルター
+        $this->assertSame($this->values[2], Collection::stream($this->values)->last(function ($value, $key) {
+            return $value['age'] === 11 or $value['age'] === 13;
+        }));
+    }
 }
 
 class CollectionObj