A charge pipe passage includes a second pipe passage part which is connected to a fuel tank by way of a first pipe passage part and extends toward the other side from one side in the vehicle widthwise direction, and a third pipe passage part which is communicably connected with the second pipe passage part on the other side in the vehicle widthwise direction and has a highest part arranged at a highest position of the charge pipe passage at an intermediate position thereof. A first check valve is interposed on the third pipe passage part downstream of the highest part, an atmospheric air introducing pipe passage is connected to the third pipe passage part upstream of the first check valve, and a second check valve is interposed on the atmospheric air introducing pipe passage at a position higher than the highest part.