To decrease further an area of a mounting hole of a coupling part of a fuel tank with a simpler structure provided.

A fuel passage 23 and a reserve fuel passage 25 allow fuel to pass through. When the fuel stored in a fuel tank is flowed to a fuel injection device or a carburetor through the fuel passage 23, the fuel from the fuel injection device or the carburetor is returned to the fuel tank through the reserve fuel passage 25. When the fuel stored in the fuel tank is flowed to the fuel injection device or the carburetor through the reserve fuel passage 25, the fuel from the fuel injection device or the carburetor is returned to the fuel tank through the fuel passage 23.