Patent ID: 8297458

Claim:
A cap comprising: a cap main body having a top wall and a skirt wall extending from an outer circumferential part of the top wall, the skirt wall being provided with an internal thread that comes in screw engagement with an external thread of a container mouth part; and a gasket made of synthetic resin for hermetically sealing the container mouth part, wherein the gasket has a top plate configured to abut a distal end part of the container mouth part to cover a distal end part, and an annular inner leg extending from the top plate, the annular inner leg being adapted to fit closely with an inner circumferential face of the container mouth part, wherein an outer circumferential edge of the top plate is continuously formed with an annular bent part that bends downward with respect to the top plate, the bent part having an inner circumferential face covering an outer circumferential face of the container mouth part, wherein the cap main body has a biasing part that biases an outer circumferential face of the bent part of the gasket in a closed state, so that the biased bent part elastically deforms to be pushed against the outer circumferential face of the container mouth part, wherein the top plate of the gasket includes a flange part disposed between the inner leg and the bent part, and the flange part is thinner than a portion of the top plate that is contiguous with an inner circumferential side of the inner leg, wherein a portion of the gasket connected to the inner circumferential side of the inner leg is positioned lower than the flange part, and wherein a top face of the top plate of the gasket is flush except for a recess part provided in a center thereof.