To safely and simply remove a battery pack mounted to a power driven tool by providing a spring between the battery pack and a housing so that it may energize the pack to run out of its operation position.

A connection sleeve 14 is integrally formed in a rear region of a frame part 15 of a motor housing 1 of a power driven tool formed in a shape of barrel opened toward a rear end while two blind-hole-like recesses are formed in a forward region, and locking elements (latch elements) 18, 19 are inserted therein through compression springs 20, 21, respectively. A slit-like through opening is formed at an outer side wall of each recess, to each of them each of inner arms 26, 27 of operation elements 22, 23 are made to face, and a battery pack 50 is locked by outer arms 24, 25 by swing operation of each of the elements 22, 23. Upon mounting the pack 50, it is energized by a spring 38 so that it may be removed.