diff --git a/rest_framework/schemas/openapi.py b/rest_framework/schemas/openapi.py
index 351174aac..6f3e854b0 100644
--- a/rest_framework/schemas/openapi.py
+++ b/rest_framework/schemas/openapi.py
@@ -378,7 +378,7 @@ class AutoSchema(ViewInspector):
                 schema['writeOnly'] = True
             if field.allow_null:
                 schema['nullable'] = True
-            if field.default and field.default != empty and not callable(field.default):
+            if field.default is not None and field.default != empty and not callable(field.default):
                 schema['default'] = field.default
             if field.help_text:
                 schema['description'] = str(field.help_text)