diff --git a/tests/unittest/test_get_max_tokens.py b/tests/unittest/test_get_max_tokens.py
new file mode 100644
index 00000000..fe2f6685
--- /dev/null
+++ b/tests/unittest/test_get_max_tokens.py
@@ -0,0 +1,67 @@
+import pytest
+from pr_agent.algo.utils import get_max_tokens, MAX_TOKENS
+import pr_agent.algo.utils as utils
+
+class TestGetMaxTokens:
+
+    # Test if the file is in MAX_TOKENS
+    def test_model_max_tokens(self, monkeypatch):
+        fake_settings = type('', (), {
+            'config': type('', (), {
+                'custom_model_max_tokens': 0,
+                'max_model_tokens': 0
+            })()
+        })()
+
+        monkeypatch.setattr(utils, "get_settings", lambda: fake_settings)
+
+        model = "gpt-3.5-turbo"
+        expected = MAX_TOKENS[model]
+
+        assert get_max_tokens(model) == expected
+
+    # Test situations where the model is not registered and exists as a custom model
+    def test_model_has_custom(self, monkeypatch):
+        fake_settings = type('', (), {
+            'config': type('', (), {
+                'custom_model_max_tokens': 5000,
+                'max_model_tokens': 0  # 제한 없음
+            })()
+        })()
+
+        monkeypatch.setattr(utils, "get_settings", lambda: fake_settings)
+
+        model = "custom-model"
+        expected = 5000
+
+        assert get_max_tokens(model) == expected
+
+    def test_model_not_max_tokens_and_not_has_custom(self, monkeypatch):
+        fake_settings = type('', (), {
+            'config': type('', (), {
+                'custom_model_max_tokens': 0,
+                'max_model_tokens': 0
+            })()
+        })()
+
+        monkeypatch.setattr(utils, "get_settings", lambda: fake_settings)
+
+        model = "custom-model"
+
+        with pytest.raises(Exception):
+            get_max_tokens(model)
+
+    def test_model_max_tokens_with__limit(self, monkeypatch):
+        fake_settings = type('', (), {
+            'config': type('', (), {
+                'custom_model_max_tokens': 0,
+                'max_model_tokens': 10000
+            })()
+        })()
+
+        monkeypatch.setattr(utils, "get_settings", lambda: fake_settings)
+
+        model = "gpt-3.5-turbo"  # this model setting is 160000
+        expected = 10000
+
+        assert get_max_tokens(model) == expected