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