PURPOSE: To integrate a battery holder and a battery pack simultaneously with the electrical connection thereof by gripping both front-rear face electrodes formed at the side face of the battery pack and the inner wall surface of insert holes, using the connecting terminals of the battery holder.

CONSTITUTION: A battery pack 1 is inserted from the lower part of a handle housing 20 in a power tool with a battery holder 22 assembled thereto. Thereupon the hook parts 18a of hook buttons 18 disposed at the lateral mounting parts 5 of a battery case 3 and energized outward by plate springs 17 while being prevented from slipping off upward by protrusions are locked to the locking parts 20a of the handle housing 20. At a connection part, the respective clamping parts 26a, 26b of spring terminals 24a, 24b clamp the U-shape parts 13 of electrode terminal plates exposed to both front and rear faces of side holes 7a, 7b and insert holes 8a, 8b. As a result, the integration of the battery pack 1 and battery holder 22 is attained simultaneously with electrical connection.