Provided is a switch box comprising: a first circuit board; a pair of bus bars provided to the first circuit board; and a first switch portion that is provided to the first circuit board and that opens and closes a circuit between the bus bars. A second circuit board can be attached to and detached from the first circuit board, and the second circuit board comprises: one bus bar; and a second switch portion that opens and closes a circuit between the one bus bar and the bus bar of the first circuit board.