A stack case of a fuel cell system includes a case body, a first end cover, and a second end cover. A recess is formed in an upper surface of the case body. An interruption control unit as an electrical equipment unit is placed in the recess. A plurality of first screw holes are formed in one end surface of the case body, and a plurality of second screw holes are formed in the other end surface of the case body. A first screw hole aligned with a recess in a direction in which a plurality of power generation cells are stacked together penetrates through the case body from one end surface of the case body to a side surface of the recess.