PURPOSE: To inexpensively provide a hammer drill having a three-mode function which can optionally select functions of only rotation, rotation and a strike, and only a strike in a switching clutch of the hammer drill having a striking mechanism part and a rotation transmitting mechanism part.

CONSTITUTION: A first gear 2 sildably loosely fitted in the shaft direction on an intermidiate shaft 3 and a rotatably loosely fitted swinging body 4, are arranged in series to each other, and striking motion can be engaged and separated by connection of claw clutches 2a and 4a. A spline groove 2b on the inner periphery of the first gear 2 and a spline part 3b of the intermediate shaft 3 engage with each other, and rotary motion can be engaged and separated. When the first gear 2 controlled by a switching lever 9 is moved to the tip side, operations of only rotation, rotation and a strike, and only a strike can be optionally selected.