Abstract: A cap device that closes a tank opening engages with an opening engagement element formed in a periphery of a tank opening. The cap device includes a handle mechanism that is rotationally mounted on a closer. The handle mechanism rotates the closer to close and open the tank opening. A torque mechanism is located between the handle mechanism and the closer and selectively transmits torque in the closing direction and the opening direction to the closer. The torque mechanism is constructed to prevent an engagement sound from being produced when the tank is being opened.

Abstract: A gasket of the invention is attached to a fuel cap and is located between a pipe sealing face of an inlet opening and a seal support element of the fuel cap to seal the fuel cap from the inlet opening. The gasket has a gasket main body and multiple sealing projections protruded from the gasket main body. The multiple sealing projections include a first pipe sealing projection and a second pipe sealing projection, which come into contact with the pipe sealing face, and a first body sealing projection and a second body sealing projection, which come into contact with the seal support element. The first pipe sealing projection is formed on a lower end of the gasket main body in its axial direction and is protruded to be pressed against the pipe sealing face in an initial stage of a closing operation.