A fuser including an endless belt, a pressurizing roller, a heater, a shaft supporting member, rotation member, and a washer. The pressurizing roller is to form a heating nip with the endless belt and is to rotate to drive the endless belt. The heater is to supply heat to the heating nip. The supporting member includes a shaft and a flange The rotation member is inserted into an inner diameter portion of the endless belt to support the endless belt, the rotation member is to be slidably rotatable with respect to the shaft. A washer interposed between the rotation member and the flange in an axial direction to regulate a movement of the endless belt in the axial direction, the washer is to slide-contact with at least one of the flange and the rotation member.