diff --git a/ChangeLog b/ChangeLog
index b35217ed6f..99bcc96393 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Sat Feb  8 15:54:12 2014  Koichi Sasada  <ko1@atdot.net>
+
+	* gc.c, gc.h (rb_objspace_marked_object_p): added.
+	  This function *ONLY* works just after marking phase,
+	  before any sweeping.
+	  This function is highly depending current GC implementation
+	  and can be removed future version.
+
 Sat Feb  8 15:41:37 2014  Tanaka Akira  <akr@fsij.org>
 
 	* lib/resolv.rb: Don't set CLOEXEC flag explicitly.  (Ruby set it by
diff --git a/gc.c b/gc.c
index f24f707026..b3ee9b7c52 100644
--- a/gc.c
+++ b/gc.c
@@ -3597,6 +3597,17 @@ rb_gc_mark(VALUE ptr)
     gc_mark(&rb_objspace, ptr);
 }
 
+/* CAUTION: THIS FUNCTION ENABLE *ONLY BEFORE* SWEEPING.
+ * This function is only for GC_END_MARK timing.
+ */
+
+int
+rb_objspace_marked_object_p(VALUE obj)
+{
+    rb_objspace_t *objspace = &rb_objspace;
+    return gc_marked(objspace, obj) ? TRUE : FALSE;
+}
+
 /* resurrect non-marked `obj' if obj is before swept */
 
 void
diff --git a/gc.h b/gc.h
index 09edafa027..ae62b091af 100644
--- a/gc.h
+++ b/gc.h
@@ -91,6 +91,7 @@ void rb_objspace_reachable_objects_from(VALUE obj, void (func)(VALUE, void *), v
 void rb_objspace_reachable_objects_from_root(void (func)(const char *category, VALUE, void *), void *data);
 int rb_objspace_markable_object_p(VALUE obj);
 int rb_objspace_internal_object_p(VALUE obj);
+int rb_objspace_marked_object_p(VALUE obj);
 
 void rb_objspace_each_objects(
     int (*callback)(void *start, void *end, size_t stride, void *data),