A fuel cell stack formed by stacking a plurality of power generation cells together in a vehicle width direction and a voltage control unit including a voltage controller and a control case are mounted in a front box of a fuel cell vehicle. The control case is joined to a stack case in a manner that the control case is provided adjacent to the stack case in a direction perpendicular to the stacking direction of the plurality of power generation cells. A cell voltage detection unit is provided between the fuel cell stack and a voltage control unit.