diff --git a/sklearn/linear_model/_passive_aggressive.py b/sklearn/linear_model/_passive_aggressive.py
index 2de019b6d986c..3a7ffbf9bfaea 100644
--- a/sklearn/linear_model/_passive_aggressive.py
+++ b/sklearn/linear_model/_passive_aggressive.py
@@ -145,6 +145,10 @@ class PassiveAggressiveClassifier(BaseSGDClassifier):
     loss_function_ : callable
         Loss function used by the algorithm.
 
+         .. deprecated:: 1.4
+            Attribute `loss_function_` was deprecated in version 1.4 and will be
+            removed in 1.6.
+
     See Also
     --------
     SGDClassifier : Incrementally trained logistic regression.