diff --git a/serde/de.py b/serde/de.py
index be905d8..a07b6ba 100644
--- a/serde/de.py
+++ b/serde/de.py
@@ -804,7 +804,11 @@ reuse_instances=reuse_instances)) if data.get("f") is not None else None'
         if arg.iterbased:
             exists = f"{arg.data} is not None"
         else:
-            exists = f'{arg.datavar}.get("{arg.conv_name()}") is not None'
+            if arg.alias:
+                aliases = (f'"{s}"' for s in [arg.name, *arg.alias])
+                exists = f'_exists_by_aliases({arg.datavar}, [{",".join(aliases)}])'
+            else:
+                exists = f'{arg.datavar}.get("{arg.conv_name()}") is not None'
         return f"({self.render(value_arg)}) if {exists} else None"
 
     def list(self, arg: DeField[Any]) -> str: