diff --git a/python-package/lightgbm/basic.py b/python-package/lightgbm/basic.py
index 6c38ee3a609a..0d494636a47a 100644
--- a/python-package/lightgbm/basic.py
+++ b/python-package/lightgbm/basic.py
@@ -3160,7 +3160,7 @@ def upper_bound(self) -> float:
 
         Returns
         -------
-        upper_bound : double
+        upper_bound : float
             Upper bound value of the model.
         """
         ret = ctypes.c_double(0)
@@ -3174,7 +3174,7 @@ def lower_bound(self) -> float:
 
         Returns
         -------
-        lower_bound : double
+        lower_bound : float
             Lower bound value of the model.
         """
         ret = ctypes.c_double(0)