PURPOSE: To provide a power tool and an improved hammer mechanism therefor capable of inhibiting vibration undesirable to a worker.

CONSTITUTION: This power tool includes a hamnner mechanism 200, and in the mechanism, a rotatable spindle 201 having axial freedom of movement in the housing 203 has several kinds of operation modes. The spindle is freely rotatable without the hammer action. The spindle may be rotated with the hammer action buffered by an elastic biasing means 213. The spindle may be rotated with non-buffered hammer action.