To close both a fuel feeding hose and an excessive fuel return hose with a single operation, to enhance the detachability of each fuel tank, and to prevent each fuel tank from being complex in structure due to the connection of the fuel feeding hose with the excessive fuel return hose.

A fuel cock 6 so constituted as to either open, or close a fuel outlet and a fuel inlet simultaneously, is provided for fuel tank 5, the fuel outlet 16 is connected with the suction port of a fuel pump set up at the outside of the fuel tank 5 using a fuel feeding hoe 23, and meanwhile, an excess fuel return hose 24 from a mixture feeding means (for example, a fuel injection device 3) set for an engine 2, is connected with the fuel inlet. In addition, the fuel outlet 16 and the opening part of the fuel inlet are opened to the inside of a fuel filter 15, so that the opening part of the fuel inlet is higher than the opening part of the fuel outlet.