Abstract: A medical syringe 2 includes a cylindrical syringe body 3 and a plunger 4 fitted in the syringe body 3 for injecting a liquid agent filled in the syringe body 3 from the syringe body 3 into the vascular system of the human body by advancing the plunger 4 relative to the syringe body 3. The plunger 4 comprising a plunger body 5 and an elastic cover 9 fitted over the plunger body 5 from the front. The plunger body 5 is provided with a backplate 62 at a rear end thereof, the backplate 62 having an annular groove 68 forwardly opened and formed in a front surface outer peripheral portion thereof. The portion of the elastic cover 9 to be rearwardly stretched by the advance of the plunger 4 is allowed to ingress into the annular groove 68 for escape.

Abstract: A glass cartridge (C) for an injection syringe prefilled with pharmaceutical liquid, wherein a glass barrel (1a) having an entrance end (1i) portion and the exit end (1e) portion are formed. Further, a stopper serving also as a piston is fitted into the glass barrel (1a), and a gasket (3) is provided on the exit end (1e). A lure lock lid (4) and a lid holder (5) are provided on the exit and (1e). An inner member (41) of the lure lock lid (4) is preferably made of polypropylene, PP while its outer member (42) is preferably made of polybutylene terephthalate, PBT. The lid holder (5) and a flanged cap (6) are preferably made of polycarbonate, PC, and the stopper (2) and the gasket (3) are made of isobutylene-isoprene copolymer rubber, IIR. Even when the glass cartridge for an injection syringe is prefilled with pharmaceutical liquid and subjected to pressurized steam sterilization (121.degree. C..times.20 min), alkaline metallic ions will be eluted.