Disclose a kind of injector for medical purpose including cap remover or the second cap. The injector for medical purpose includes the injector housing for limiting reservoir, plunger rod and the plug for engaging and being slidably disposed in reservoir with a part of plunger rod. Sealing engagement that offer with the side wall of injector housing be provided of the plug relative to the inside of injector housing. The injector for medical purpose further includes the first cap of the sharp first end of the needle with sharp first end and the second end being connected to reservoir, covering needle and at least part of second cap for covering the first cap. Second cap is engaged with the first cap, so that the second cap removes while removes the first cap from the first end of needle.
