diff --git a/ruby/red-arrow-format/lib/arrow-format/type.rb b/ruby/red-arrow-format/lib/arrow-format/type.rb
index d9e427a0d50..d348a09da5c 100644
--- a/ruby/red-arrow-format/lib/arrow-format/type.rb
+++ b/ruby/red-arrow-format/lib/arrow-format/type.rb
@@ -716,6 +716,11 @@ def initialize(unit)
       @unit = unit
     end
 
+    def ==(other)
+      other.is_a?(self.class) and
+        @unit == other.unit
+    end
+
     def name
       "Duration"
     end
diff --git a/ruby/red-arrow-format/test/test-duration-type.rb b/ruby/red-arrow-format/test/test-duration-type.rb
new file mode 100644
index 00000000000..753c9e6b8ea
--- /dev/null
+++ b/ruby/red-arrow-format/test/test-duration-type.rb
@@ -0,0 +1,30 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+class TestDurationType < Test::Unit::TestCase
+  sub_test_case("#==") do
+    def test_equal
+      assert_equal(ArrowFormat::DurationType.new(:second),
+                   ArrowFormat::DurationType.new(:second))
+    end
+
+    def test_not_equal
+      assert_not_equal(ArrowFormat::DurationType.new(:second),
+                       ArrowFormat::DurationType.new(:millisecond))
+    end
+  end
+end