Abstract: A retractable safety syringe includes primarily a barrel, a seat, and a push rod, wherein a tubular exit is located at an end of the barrel, a bore is located at an inner rim of bottom of exit, a thin breakage part is located at a periphery of the end, and a groove is located on a surface of barrel close to the end for latching and fixing a cover. A bolt is located at a top end of the push rod, so as to retract the push rod by locking the bolt of push rod into the bore at the inner rim of exit of barrel, after accomplishing an injection with the syringe, thereby breaking the breakage part at the periphery of barrel from a stretching force and retracting a needle into the barrel, in order to prevent the used syringe from being recycled.

Abstract: A disposable safety syringe structure includes a barrel, a needle seat, a plunger, and a protective cover. A circumferentially surrounded thin broken portion is disposed on a periphery of an end portion of the barrel, and a circular groove is disposed on the end portion of the barrel thereby fastening the protective cover. In addition, a vertical cutter is disposed on a bottom end of the protective cover, and a fastener is disposed on a top end of the plunger, such that the syringe can be hooked onto an opening of the outlet of the barrel by means of the fastener of the plunger after injection. When the protective cover is turned, the cutter cuts off the broken portion such that the needle head is retracted to the barrel and the barrel can be completely destroyed in order to prevent it from being recycled and reused.