FUEL TANK CAP

A fuel tank cap includes: a cap body which opens and closes a fuel supply port of a fuel tank; a ring member which is disposed around the fuel supply port and is shaped so as to surround the cap body; and a hinge member which is coupled to the ring member to support the cap body in a turnable manner between a closed position and an open position. A first peripheral part of the ring member, which is opposed to an outer periphery of the cap body, has a larger dimension in a circumferential direction than a dimension of a second peripheral part of the hinge member, which is opposed to the outer periphery of the cap body. The ring member and the hinge member are made of mutually different materials.