The present invention aims to provide a gasket for a pre-filled syringe which has excellent air-tightness and liquid-tightness and a mold for forming the gasket. The present invention relate to a mold for a gasket laminated with an inactive film for a pre-filled syringe, wherein at least a surface of the mold which forms a seal sliding surface of an annular protrusion of the gasket is mirror finished to have an arithmetic mean roughness Ra of less than 0.03 µm.