The present invention provides a gasket for prefilled syringes having both airtightness and operability. The present invention relates to a gasket for prefilled syringes, the gasket including a plurality of circular ribs that are to be in sliding contact with the inner wall of a syringe, the gasket being laminated with an inert film, the plurality of circular ribs including a front circular rib having a front corner with a radius of curvature R1 and a rear corner with a radius of curvature R2, a ratio of the radius of curvature R2 to the radius of curvature R1 being more than 1.
