Abstract: The present invention relates to a gasket and an object of the present invention is to provide a gasket capable of providing an excellent slidability and holding its sealability without applying lubricant and a gasket that can prevent a resin film from being peeled off of a gasket body and prevent the generation of a molding defect such as pinholes. The object can be attained according to a gasket installed slidably in an outer tube of a syringe, including a gasket body and a resin film formed of a material lower in coefficient of friction than a material of the gasket body, which covers at least an outer periphery of the gasket body, in which when a surface roughness of the resin film on the outer tube side is defined as Ra1 and a surface roughness of the resin film on the gasket body side is defined as Ra2, a relationship of 1.5 Ra1≦Ra2 is satisfied.