A power tool (101, 201) adapted for detachably coupling a tool bit (119, 219) that is designed as a hammer bit that performs the operation by applying a linear impact force to the workpiece, the power tool (101, 201) comprising: a first operating mechanism (113, 213) that linearly drives the tool bit (119, 219) and thereby causes the tool bit (119, 219) to perform a predetermined operation, a dynamic vibration reducer (151, 251) that reduces vibration in the operation of the tool bit (119, 219) via a weight (153, 253) that reciprocates under the action of a biasing force of an elastic element (157, 257), a second operating mechanism (116, 216) that includes a slider (167, 267) that supports one end of the elastic element (157, 257) and is caused to reciprocate and thereby excites the elastic element (157, 257) to thereby forcibly drive the weight (153, 253), and a driving motor (111, 211), wherein the elastic element is a biasing spring (157, 257), the first operating mechanism (113, 213) includes a first driving mechanism (126, 226) that converts a rotating output of the driving motor (111, 211) into a linear motion in the axial direction of the tool bit (119, 219), and a striker (115, 215) that is caused to reciprocate by the first driving mechanism (126, 226) and thereby drives the tool bit (119,219), the second operating mechanism includes a second driving mechanism (161, 263) that converts a rotating output of the driving motor (111, 211) into a linear motion in the axial direction of the tool bit (119, 219), wherein the slider (167, 267) is caused to reciprocate by the second driving mechanism, and wherein the second driving mechanism (161, 263) comprises an eccentric element (161, 263), and the eccentric element (161, 263) is adjusted and the phase of the eccentric element (161, 263) is adjusted in order to adjust the timing of excitation of the elastic element (157, 257), characterised in that the striker (115, 215) drives the tool bit (119, 219) by the action of an air spring, wherein the time at which the slider (167, 267) presses the elastic element (157, 257) or the time at which an excitation force is inputted to the weight (153, 253) is set allowing time delay resulting from the compression time required for actuating the air spring. a first operating mechanism (113, 213) that linearly drives the tool bit (119, 219) and thereby causes the tool bit (119, 219) to perform a predetermined operation, a dynamic vibration reducer (151, 251) that reduces vibration in the operation of the tool bit (119, 219) via a weight (153, 253) that reciprocates under the action of a biasing force of an elastic element (157, 257), a second operating mechanism (116, 216) that includes a slider (167, 267) that supports one end of the elastic element (157, 257) and is caused to reciprocate and thereby excites the elastic element (157, 257) to thereby forcibly drive the weight (153, 253), and a driving motor (111, 211), wherein the elastic element is a biasing spring (157, 257), the first operating mechanism (113, 213) includes a first driving mechanism (126, 226) that converts a rotating output of the driving motor (111, 211) into a linear motion in the axial direction of the tool bit (119, 219), and a striker (115, 215) that is caused to reciprocate by the first driving mechanism (126, 226) and thereby drives the tool bit (119,219), the second operating mechanism includes a second driving mechanism (161, 263) that converts a rotating output of the driving motor (111, 211) into a linear motion in the axial direction of the tool bit (119, 219), wherein the slider (167, 267) is caused to reciprocate by the second driving mechanism, and wherein the second driving mechanism (161, 263) comprises an eccentric element (161, 263), and the eccentric element (161, 263) is adjusted and the phase of the eccentric element (161, 263) is adjusted in order to adjust the timing of excitation of the elastic element (157, 257), characterised in that the striker (115, 215) drives the tool bit (119, 219) by the action of an air spring, wherein the time at which the slider (167, 267) presses the elastic element (157, 257) or the time at which an excitation force is inputted to the weight (153, 253) is set allowing time delay resulting from the compression time required for actuating the air spring.