To prevent the loss of a cover member by installing a means for fixing the cover member to a battery member in the state in which it is removed from a box main body on the inside of the cover member.

When a battery 8 is set on the bottom inside of a housing cover 7, the inner walls of projecting parts 7d-7e are fit to the side outer wall to make right and left positioning. In addition, as the battery 8 is moved in the arrow direction, locking claws of elastic pieces 7d-1 to 7e-1 are engaged with recessed parts 8c, 8d of the battery 8 by snapping fit, and the housing cover 7 is held in the vertical directions by the battery 8. By fixing the housing cover 7 so as to cover the top surface of the battery 8, a power source terminal on the top surface of the battery is protected with the housing cover 7. The need for an exclusive cover for protecting the power source terminal of the battery 8 can be eliminated.