LOCK MECHANISM OF BATTERY PACK

A locking mechanism of a battery pack A is provided with a hook 14 which can be locked to a mounting part B of an object equipment such as an electric tool in a state slid with respect to the mounting part, and operation parts 16 for releasing the lock which are linked to the hook 14, on a case which contains a battery. The hook 14 is urged to move upward by an elastic body in a direction of being locked to the mounting part B. The operation parts 16 are arranged in both side parts of the case within such a range that they can be grasped with a single hand from both sides of a backward end in the sliding direction of the case. When the operation parts 16 are operated from the both sides, the lock between the hook 14 and the mounting part B is released against the urge by the elastic body.