The present invention relates to a disposable syringe, and more particularly to a disposable syringe having a syringe barrel (10) having one side opened and a chemical solution inlet (15) protruded on the other side, And a piston which is in close contact with the inner peripheral edge of the syringe barrel 10 in a state of being engaged with the piston fixing table 21 of the plunger 20 and sucks and discharges the medicine to the inside and outside of the syringe barrel 10, An injector needle 40 for injecting a drug inside the syringe barrel 10 when the piston 30 is pressurized by a needle needle 42 coupled to a drug solution injection port 15 of the injector； A coupling portion 44 is formed on the inner circumferential surface of the needle hub 42 and a corresponding coupling portion 16 is formed on the outer circumferential surface of the chemical liquid injection port 15 of the syringe to be coupled to the coupling portion 44, On the outer surface of the plunger (21) of the plunger (20) And a connecting protrusion 24 having a diameter slightly larger than the diameter or width of the connecting block 22 is formed at the distal end of the connecting block 22 so as to be fitted to one side of the piston 30. [ And a first locking protrusion 12 having a predetermined height is formed at a position spaced from the inner end of the syringe barrel 10 by a predetermined distance so that the plunger 20 to which the piston 30 is coupled is inserted into the inner side of the syringe barrel 10 The outer edge of the piston 30 is caught by the first locking protrusion 12 so that the piston 30 is detached from the coupling protrusion 24 of the connecting rod 22 .본 고안은 일회용 주사기에 관한 것으로, 더욱 상세하게는 일측이 개구되고 타측에 약액주입구(15)가 돌출된 주사기 외통(10)과, 상기 주사기 외통(10)의 개구부 내측으로 삽입되어 왕복 이동가능한 일정 길이의 플런저(20)와, 상기 플런저(20)의 피스톤고정대(21)에 결합된 상태로 주사기외통(10)의 내주연과 밀착되어 주사기외통(10)의 내외측으로 약물을 흡입,배출시키는 피스톤(30)과, 상기 주사기의 약액주입구(15)에 주사바늘허브(42)가 결합되어 상기 피스톤(30)의 가압시 주사기 외통(10) 내부의 약물을 환자에게 주입시키는 주사바늘(40)；을 포함하되,
