diff --git a/lib/fluent/plugin/parser_syslog.rb b/lib/fluent/plugin/parser_syslog.rb
index 954df0fa2f..778818a145 100644
--- a/lib/fluent/plugin/parser_syslog.rb
+++ b/lib/fluent/plugin/parser_syslog.rb
@@ -27,8 +27,8 @@ class SyslogParser < Parser
       REGEXP = /^(?<time>[^ ]*\s*[^ ]* [^ ]*) (?<host>[^ ]*) (?<ident>[^ :\[]*)(?:\[(?<pid>[0-9]+)\])?(?:[^\:]*\:)? *(?<message>.*)$/
       # From in_syslog default pattern
       REGEXP_WITH_PRI = /^\<(?<pri>[0-9]+)\>(?<time>[^ ]* {1,2}[^ ]* [^ ]*) (?<host>[^ ]*) (?<ident>[^ :\[]*)(?:\[(?<pid>[0-9]+)\])?(?:[^\:]*\:)? *(?<message>.*)$/
-      REGEXP_RFC5424 = /\A^(?<time>[^ ]+) (?<host>[^ ]+) (?<ident>[^ ]+) (?<pid>.{1,128}) (?<msgid>[^ ]+) (?<extradata>(\[(.*)\]|[^ ])) (?<message>.+)$\z/
-      REGEXP_RFC5424_WITH_PRI = /\A^\<(?<pri>[0-9]{1,3})\>[1-9]\d{0,2} (?<time>[^ ]+) (?<host>[^ ]+) (?<ident>[^ ]+) (?<pid>.{1,128}) (?<msgid>[^ ]+) (?<extradata>(\[(.*)\]|[^ ])) (?<message>.+)$\z/
+      REGEXP_RFC5424 = /\A^(?<time>[^ ]+) (?<host>[!-~]{1,255}) (?<ident>[!-~]{1,48}) (?<pid>[!-~]{1,128}) (?<msgid>[!-~]{1,32}) (?<extradata>(?:\-|\[(.*)\]))(?: (?<message>.+))?$\z/
+      REGEXP_RFC5424_WITH_PRI = /\A^\<(?<pri>[0-9]{1,3})\>[1-9]\d{0,2} (?<time>[^ ]+) (?<host>[!-~]{1,255}) (?<ident>[!-~]{1,48}) (?<pid>[!-~]{1,128}) (?<msgid>[!-~]{1,32}) (?<extradata>(?:\-|\[(.*)\]))(?: (?<message>.+))?$\z/
       REGEXP_DETECT_RFC5424 = /^\<.*\>[1-9]\d{0,2}/
 
       config_set_default :time_format, "%b %d %H:%M:%S"
diff --git a/test/plugin/test_parser_syslog.rb b/test/plugin/test_parser_syslog.rb
index 7373000138..1d53df5397 100644
--- a/test/plugin/test_parser_syslog.rb
+++ b/test/plugin/test_parser_syslog.rb
@@ -118,6 +118,23 @@ def test_parse_with_rfc5424_message_and_without_priority
                    @parser.instance.patterns['format'])
     end
 
+    def test_parse_with_rfc5424_empty_message_and_without_priority
+      @parser.configure(
+                        'time_format' => '%Y-%m-%dT%H:%M:%S.%L%z',
+                        'message_format' => 'rfc5424',
+                        )
+      text = '2017-02-06T13:14:15.003Z 192.168.0.1 fluentd - - -'
+      @parser.instance.parse(text) do |time, record|
+        assert_equal(event_time("2017-02-06T13:14:15.003Z", format: '%Y-%m-%dT%H:%M:%S.%L%z'), time)
+        assert_equal "-", record["pid"]
+        assert_equal "-", record["msgid"]
+        assert_equal "-", record["extradata"]
+        assert_nil record["message"]
+      end
+      assert_equal(Fluent::Plugin::SyslogParser::REGEXP_RFC5424,
+                   @parser.instance.patterns['format'])
+    end
+
     def test_parse_with_rfc5424_message_without_time_format
       @parser.configure(
                         'message_format' => 'rfc5424',
@@ -133,6 +150,21 @@ def test_parse_with_rfc5424_message_without_time_format
       end
     end
 
+    def test_parse_with_rfc5424_message_with_priority_and_pid
+      @parser.configure(
+                        'message_format' => 'rfc5424',
+                        'with_priority' => true,
+                        )
+      text = '<28>1 2018-09-26T15:54:26.620412+09:00 machine minissdpd 1298 - -  peer 192.168.0.5:50123 is not from a LAN'
+      @parser.instance.parse(text) do |time, record|
+        assert_equal(event_time("2018-09-26T15:54:26.620412+0900", format: '%Y-%m-%dT%H:%M:%S.%L%z'), time)
+        assert_equal "1298", record["pid"]
+        assert_equal "-", record["msgid"]
+        assert_equal "-", record["extradata"]
+        assert_equal " peer 192.168.0.5:50123 is not from a LAN", record["message"]
+      end
+    end
+
     def test_parse_with_rfc5424_structured_message
       @parser.configure(
                         'time_format' => '%Y-%m-%dT%H:%M:%S.%L%z',
@@ -142,13 +174,64 @@ def test_parse_with_rfc5424_structured_message
       text = '<16>1 2017-02-06T13:14:15.003Z 192.168.0.1 fluentd 11111 ID24224 [exampleSDID@20224 iut="3" eventSource="Application" eventID="11211"] Hi, from Fluentd!'
       @parser.instance.parse(text) do |time, record|
         assert_equal(event_time("2017-02-06T13:14:15.003Z", format: '%Y-%m-%dT%H:%M:%S.%L%z'), time)
-assert_equal "11111", record["pid"]
+        assert_equal "11111", record["pid"]
         assert_equal "ID24224", record["msgid"]
         assert_equal "[exampleSDID@20224 iut=\"3\" eventSource=\"Application\" eventID=\"11211\"]",
                      record["extradata"]
         assert_equal "Hi, from Fluentd!", record["message"]
       end
     end
+
+    def test_parse_with_rfc5424_multiple_structured_message
+      @parser.configure(
+                        'time_format' => '%Y-%m-%dT%H:%M:%S.%L%z',
+                        'message_format' => 'rfc5424',
+                        'with_priority' => true,
+                        )
+      text = '<16>1 2017-02-06T13:14:15.003Z 192.168.0.1 fluentd 11111 ID24224 [exampleSDID@20224 iut="3" eventSource="Application" eventID="11211"][exampleSDID@20224 class="high"] Hi, from Fluentd!'
+      @parser.instance.parse(text) do |time, record|
+        assert_equal(event_time("2017-02-06T13:14:15.003Z", format: '%Y-%m-%dT%H:%M:%S.%L%z'), time)
+        assert_equal "11111", record["pid"]
+        assert_equal "ID24224", record["msgid"]
+        assert_equal "[exampleSDID@20224 iut=\"3\" eventSource=\"Application\" eventID=\"11211\"][exampleSDID@20224 class=\"high\"]",
+                     record["extradata"]
+        assert_equal "Hi, from Fluentd!", record["message"]
+      end
+    end
+
+    def test_parse_with_rfc5424_message_includes_right_bracket
+      @parser.configure(
+                        'time_format' => '%Y-%m-%dT%H:%M:%S.%L%z',
+                        'message_format' => 'rfc5424',
+                        'with_priority' => true,
+                        )
+      text = '<16>1 2017-02-06T13:14:15.003Z 192.168.0.1 fluentd 11111 ID24224 [exampleSDID@20224 iut="3" eventSource="Application" eventID="11211"] Hi, from Fluentd]!'
+      @parser.instance.parse(text) do |time, record|
+        assert_equal(event_time("2017-02-06T13:14:15.003Z", format: '%Y-%m-%dT%H:%M:%S.%L%z'), time)
+        assert_equal "11111", record["pid"]
+        assert_equal "ID24224", record["msgid"]
+        assert_equal "[exampleSDID@20224 iut=\"3\" eventSource=\"Application\" eventID=\"11211\"]",
+                     record["extradata"]
+        assert_equal "Hi, from Fluentd]!", record["message"]
+      end
+    end
+
+    def test_parse_with_rfc5424_empty_message
+      @parser.configure(
+                        'time_format' => '%Y-%m-%dT%H:%M:%S.%L%z',
+                        'message_format' => 'rfc5424',
+                        'with_priority' => true,
+                        )
+      text = '<16>1 2017-02-06T13:14:15.003Z 192.168.0.1 fluentd 11111 ID24224 [exampleSDID@20224 iut="3" eventSource="Application" eventID="11211"]'
+      @parser.instance.parse(text) do |time, record|
+        assert_equal(event_time("2017-02-06T13:14:15.003Z", format: '%Y-%m-%dT%H:%M:%S.%L%z'), time)
+        assert_equal "11111", record["pid"]
+        assert_equal "ID24224", record["msgid"]
+        assert_equal "[exampleSDID@20224 iut=\"3\" eventSource=\"Application\" eventID=\"11211\"]",
+                     record["extradata"]
+        assert_nil record["message"]
+      end
+    end
   end
 
   class TestAutoRegexp < self