diff --git a/sklearn/preprocessing/_function_transformer.py b/sklearn/preprocessing/_function_transformer.py
index c49684d0ebfbc..76fd94b54cf43 100644
--- a/sklearn/preprocessing/_function_transformer.py
+++ b/sklearn/preprocessing/_function_transformer.py
@@ -194,7 +194,7 @@ def _check_inverse_transform(self, X):
 
         if not all(np.issubdtype(d, np.number) for d in dtypes):
             raise ValueError(
-                "'check_inverse' is only supported when all the elements in `X` is"
+                "'check_inverse' is only supported when all the elements in `X` are"
                 " numerical."
             )
 
diff --git a/sklearn/preprocessing/tests/test_function_transformer.py b/sklearn/preprocessing/tests/test_function_transformer.py
index 81d9d0b8eb843..792e766858fea 100644
--- a/sklearn/preprocessing/tests/test_function_transformer.py
+++ b/sklearn/preprocessing/tests/test_function_transformer.py
@@ -209,7 +209,7 @@ def inverse_func(X):
         func=func, inverse_func=inverse_func, validate=False, check_inverse=True
     )
 
-    msg = "'check_inverse' is only supported when all the elements in `X` is numerical."
+    msg = "'check_inverse' is only supported when all the elements in `X` are numerical."
     with pytest.raises(ValueError, match=msg):
         transformer.fit(data)
 
@@ -239,7 +239,7 @@ def test_function_transformer_with_dataframe_and_check_inverse_True():
     )
 
     df_mixed = pd.DataFrame({"a": [1, 2, 3], "b": ["a", "b", "c"]})
-    msg = "'check_inverse' is only supported when all the elements in `X` is numerical."
+    msg = "'check_inverse' is only supported when all the elements in `X` are numerical."
     with pytest.raises(ValueError, match=msg):
         transformer.fit(df_mixed)