The locking device is for arrangement in the connector receptacle, which is connected to the charging connector that charges a battery, to interlock the connector receptacle and the charging connector. The locking device includes a notch engageable with a hook arranged in the charging connector. A lock bar is movable between a lock position, at which the lock bar restricts movement of the hook and keeps the hook and lock bar engaged, and an unlock position, at which the lock bar moves away from the hook and permits movement of the hook. A drive unit generates drive force for moving the lock bar from the unlock position to the lock position.