A retractable device of a safety syringe comprises a barrel (10), a set of needle seats (20,30,40) and a plunger (50), wherein the set of needle seats (20,30,40) can be located steady at the open end of the barrel (10). With locking members and tabling linked members between any two of the set of needle seats (20,30,40), a plunger head (57) can be engaged with the set of needle seats (20,30,40), so that the injection needle (60) can be retracted.
