The present invention provides a gasket for a pre filled syringe whereby airtightness and operability are achieved at the same time. The present invention relates to a gasket built up by layers of inert films having a plurality of annular ribs for sliding against an inside wall of a syringe the gasket for a pre filled syringe characterized in that the ratio of the curvature radius (R2) of a rear end angular part of a distal end annular rib to the curvature radius (R1) of a distal end angular part is greater than 1.
