diff --git a/gokart/task.py b/gokart/task.py
index 43562f64..0aba0e8f 100644
--- a/gokart/task.py
+++ b/gokart/task.py
@@ -375,7 +375,7 @@ def make_unique_id(self) -> str:
         return unique_id
 
     def to_str_params(self, only_significant=False, only_public=False):
-        if only_significant == True and only_public == False:
+        if only_significant and (not only_public):
             # cache to_str_params to avoid too slow task creation of deep task tree
             # e.g. gokart.build(RecursiveTask(dep=RecursiveTask(dep=RecursiveTask(dep=HelloWorldTask())))) takes O(n*n) to_str_params calls
             if self._str_params_cache is not None:
diff --git a/test/test_task_on_kart.py b/test/test_task_on_kart.py
index e3946b49..78a918f3 100644
--- a/test/test_task_on_kart.py
+++ b/test/test_task_on_kart.py
@@ -582,6 +582,17 @@ def test_serialize_and_deserialize_default_values(self):
         deserialized: gokart.TaskOnKart = luigi.task_register.load_task(None, task.get_task_family(), task.to_str_params())
         self.assertDictEqual(task.to_str_params(), deserialized.to_str_params())
 
+    def test_to_str_params_changes_on_values_and_flags(self):
+        class _DummyTaskWithParams(gokart.TaskOnKart):
+            task_namespace = __name__
+            param: str = luigi.Parameter()
+
+        t1 = _DummyTaskWithParams(param='a')
+        self.assertEqual(t1.to_str_params(), t1.to_str_params())  # cache
+        self.assertEqual(t1.to_str_params(), _DummyTaskWithParams(param='a').to_str_params())  # same value
+        self.assertNotEqual(t1.to_str_params(), _DummyTaskWithParams(param='b').to_str_params())  # different value
+        self.assertNotEqual(t1.to_str_params(), t1.to_str_params(only_significant=True))
+
     def test_should_lock_run_when_set(self):
         class _DummyTaskWithLock(gokart.TaskOnKart):
             def run(self):