PURPOSE: To prevent forgetting to set a battery stopper while securely restraining a battery by providing a locking member which restrains the restricting posture of said battery stopper when a battery cover is closed, on said cover.

CONSTITUTION: The opening for putting in and out a battery, of a battery housing part 1 in which a battery 5 is being housed, is closed by a battery cover 7. On the other hand, the battery 5 which is housed in the battery housing part 1, is restrained by a battery stopper 13. The move of the battery stopper 13 is restrained by a locking member 19, which is fixed to the back of the battery 5, and is brought to the underside of the free end part side 13a of the battery stopper 13 when the battery cover 7 is closed. If one forgets to set the locking device after housing the battery 5, the locking member 19 interferes with the free end part 13a of the battery stopper 13, making one notice it.