diff --git a/test/util/lemmatizer/lemmatizer_test.dart b/test/util/lemmatizer/lemmatizer_test.dart
new file mode 100644
index 0000000..8d19f73
--- /dev/null
+++ b/test/util/lemmatizer/lemmatizer_test.dart
@@ -0,0 +1,51 @@
+import 'package:jadb/util/lemmatizer/lemmatizer.dart';
+import 'package:jadb/util/lemmatizer/rules/godan_verbs.dart';
+import 'package:jadb/util/lemmatizer/rules/ichidan_verbs.dart';
+import 'package:test/test.dart';
+
+const List<String> ichidanVerbs = [
+  '食べる',
+  '食べた',
+  '食べさせられた',
+  '食べたい',
+  '食べたくない',
+  '食べたくなかった',
+];
+const List<String> godanVerbs = [
+  '泳ぐ',
+  '泳いだ',
+  '泳げる',
+  // '泳げれた',
+];
+
+bool findRuleRecursively(Lemmatized result, LemmatizationRule expectedRule) {
+  if (result.rule == expectedRule) {
+    return true;
+  }
+
+  for (final c in result.children) {
+    if (findRuleRecursively(c, expectedRule)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void main() {
+  group('Lemmatize Ichidan Verbs', () {
+    for (final v in ichidanVerbs) {
+      test('Lemmatize Ichidan Verb $v', () {
+        expect(findRuleRecursively(lemmatize(v), ichidanVerbBase), true);
+      });
+    }
+  });
+
+  group('Lemmatize Godan Verbs', () {
+    for (final v in godanVerbs) {
+      test('Lemmatize Godan Verb $v', () {
+        expect(findRuleRecursively(lemmatize(v), godanVerbBase), true);
+      });
+    }
+  });
+}
diff --git a/test/util/lemmatizer/rules/godan_verbs_test.dart b/test/util/lemmatizer/rules/godan_verbs_test.dart
new file mode 100644
index 0000000..5791cb6
--- /dev/null
+++ b/test/util/lemmatizer/rules/godan_verbs_test.dart
@@ -0,0 +1,14 @@
+import 'package:jadb/util/lemmatizer/rules/godan_verbs.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Test Godan Verb Base Rule', () {
+    expect(godanVerbBase.matches('泳ぐ'), true);
+    expect(godanVerbBase.apply('泳ぐ'), ['泳ぐ']);
+  });
+
+  test('Test Godan Verb Negative Rule', () {
+    expect(godanVerbNegative.matches('泳がない'), true);
+    expect(godanVerbNegative.apply('泳がない'), ['泳ぐ']);
+  });
+}
diff --git a/test/util/lemmatizer/rules/i_adjectives_test.dart b/test/util/lemmatizer/rules/i_adjectives_test.dart
new file mode 100644
index 0000000..fa098cd
--- /dev/null
+++ b/test/util/lemmatizer/rules/i_adjectives_test.dart
@@ -0,0 +1,15 @@
+import 'package:jadb/util/lemmatizer/rules/i_adjectives.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Test i-adjective Base Rule', () {
+    expect(iAdjectiveBase.matches('怪しい'), true);
+    expect(iAdjectiveBase.apply('怪しい'), ['怪しい']);
+  });
+
+
+  test('Test i-adjective Negative Rule', () {
+    expect(iAdjectiveNegative.matches('怪しくない'), true);
+    expect(iAdjectiveNegative.apply('怪しくない'), ['怪しい']);
+  });
+}
diff --git a/test/util/lemmatizer/rules/ichidan_verbs_test.dart b/test/util/lemmatizer/rules/ichidan_verbs_test.dart
new file mode 100644
index 0000000..7f6a90c
--- /dev/null
+++ b/test/util/lemmatizer/rules/ichidan_verbs_test.dart
@@ -0,0 +1,14 @@
+import 'package:jadb/util/lemmatizer/rules/ichidan_verbs.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Test Ichidan Verb Base Rule', () {
+    expect(ichidanVerbBase.matches('食べる'), true);
+    expect(ichidanVerbBase.apply('食べる'), ['食べる']);
+  });
+
+  test('Test Ichidan Verb Negative Rule', () {
+    expect(ichidanVerbNegative.matches('食べない'), true);
+    expect(ichidanVerbNegative.apply('食べない'), ['食べる']);
+  });
+}
diff --git a/test/util/lemmatizer/rules_test.dart b/test/util/lemmatizer/rules_test.dart
new file mode 100644
index 0000000..c4bd430
--- /dev/null
+++ b/test/util/lemmatizer/rules_test.dart
@@ -0,0 +1,15 @@
+import 'package:jadb/util/lemmatizer/lemmatizer.dart';
+import 'package:jadb/util/lemmatizer/rules.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Assert lemmatizerRulesByWordClass is correct', () {
+    for (final entry in lemmatizationRulesByWordClass.entries) {
+      final WordClass wordClass = entry.key;
+      final List<LemmatizationRule> rules = entry.value;
+      for (final LemmatizationRule rule in rules) {
+        expect(wordClass, rule.wordClass);
+      }
+    }
+  });
+}