Abstract: A single-usage disposable hypodermic syringe in which the needle cover of the conventional syringe is replaced by a tubular housing which encloses from the tip of the needle cannula to the rear end of the barrel. An empty space is reserved inside the needle locking base for the positioning of a plug. When an arc segment of a projected member located at the front of the plunger is moved forward with the plunger, the plug with the channel is being pushed to the bottom of the empty space, allowing the plug to rotate and block off the opening of the needle cannula. The medication can no longer be given. A triangular plate installed in the rear portion of the Y-shaped plunger is used to restrict the movement of the projecting plate. Only when the projecting plate is rotated and swing away that the syringe is able to accept medication. The syringe cannot be reused and the tubular housing is used to cover the overall syringe for disposal.