Abstract: An injection syringe generally comprised of a multichambered cylindrical ampule, a tripartite case of a front case; a middle case; a rear case, and a needle-holder, and a plunger: the multichambered cylindrical ampule including two chambers of a front space and a rear space, the front space being sealed forwardly with a packing penetrable by a needle and sealed rearwardly with a movable front gasket, and the rear space being sealed forwardly with the front gasket and sealed rearwardly with a movable rear gasket, and the ampule also including a bypass route longitudinally arranged on inner surface of the ampule such that the front gasket is located to take a position rearwardly apart from the bypass route before dissolution of a solid medicine, wherein the front space for admission of the solid medicine is separated from the rear space for admission of a medicinal solvent or dispersing agent; the middle case also including a short thread or fixer means provided externally at midportion thereof, and the rear ca

Abstract: A syringe comprises, besides a barrel, a plunger and a needle, a needle holding stopper, a needle hole stopper, a spring connecting the needle holding stopper and needle hole stopper and a lock mechanism provided between the barrel and the needle holding stopper. The lock mechanism functions such that it fixes the needle holding stopper until completion of injection so that the needle is not pushed up into the hinder part of the barrel, and that it is released when the plunger is further pressed, i.e. by a single finger motion, after completion of the injection, so that the needle holding stopper is pushed up by force of the spring, thereby hangaring the needle in the barrel and, at the same time, the needle hole stopper is moved to close the needle hold on the end of the barrel. The syringe causes no accidental pricking of a finger with the needle after injection operation or oozing out of the blood or the like of the patient adhered on the needle tip.