An output cable for transferring an output of a fuel cell stack to a device provided outside a stack case and an output terminal portion of the fuel cell stack are connected to each other, and a blocking device capable of blocking the fuel cell stack from supplying the output thereof to the device through mechanical operation from outside the stack case is provided. In the stack case, a first through hole for allowing for maintenance and checkout from the outside of the stack case to the inside is formed, and the blocking device is attached so as to cover this first through hole from outside. The blocking device includes a housing made of a solid body, a second through hole for communicating the outside of the stack case with the inside by communicating with the first through hole, and a closing cover for closing the second through hole.