The invention discloses a power tool, which comprises a machine shell, a driving shaft arranged on the machine shell, and a clamping chuck connected to the driving shaft, wherein the clamping chuck comprises a central body which is provided with a head part and a tail part, the tail part is arranged to match the driving shaft so that the central body rotates along with the driving shaft, and the head part comprises an axial hole and a plurality of passages which are arranged to form angles and are intersectant with the axial hole; a plurality of detents are positioned in each passage in a sliding mode, and each detent comprises a detent surface formed on one side and screw threads formed on the opposite side; a nut is rotatably arranged on the central body through fit with the screw threads on the detents so that the rotation of the nut drives the detents to move axially in the passages; and a clutch mechanism is arranged on the machine shell and comprises at least one radial moving piece. The power tool has smaller length and a compact structure.