An impact tool which is adapted to drive a tool bit in a longitudinal direction of the tool bit and to perform a predetermined operation, comprising: a motor which includes a motor shaft, a driving mechanism (140, 151) which is adapted to be driven by the motor and is adapted to drive the tool bit, a main housing which houses the driving mechanism (140, 151), a handle which includes a grip portion (109 A) extending in a cross direction crossing the longitudinal direction of the tool bit, a weight which is housed in the main housing and movable with respect to the main housing, a first crank mechanism which has a first rotation shaft and a first eccentric shaft which is offset from the rotational center of the first rotation shaft, the first crank mechanism being configured to be driven by the motor and drive the driving mechanism (140, 151), and a second crank mechanism which has a second eccentric shaft, a movable plate and a guide pin, which is fixed on the main housing, the second crank mechanism being configured to be driven by the motor and drive the weight via the movable plate such that the weight is relatively moved with respect to the main housing, wherein the second eccentric shaft is fitted onto the first rotation shaft and connected by a connection member wherein the second eccentric shaft is offset from the rotational center of the first rotation shaft, wherein the movable plate comprises an engagement hole engaged with the second eccentric shaft, a first guide hole engaged with the guide pin and push arms for driving the weight, wherein the weight is configured to reduce vibration generated on the main housing during the operation by relatively moving with respect to the main housing, an upper connection part is formed on one end of the grip portion in an extending direction of the grip portion, and a lower connection part is formed on another end of the grip portion in the extending direction of the grip portion, characterized in that the movable plate further comprises a second guide hole, which is engaged with an intermediate shaft of the driving mechanism, wherein the movable plate is guided in the longitudinal direction of the tool bit by the guide holes (255, 254), the handle is configured to be moved with respect to the main housing, each of the upper connection part and the lower connection part are connected to the main housing via a compression coil spring arranged between the main housing and the handle and applying a biasing force on the handle, and the handle is configured to prevent vibration transmission from the main housing to the handle during the operation by relatively moving with respect to the main housing in a state that the biasing force of the compression coil springs is applied on the handle. a motor which includes a motor shaft, a driving mechanism (140, 151) which is adapted to be driven by the motor and is adapted to drive the tool bit, a main housing which houses the driving mechanism (140, 151), a handle which includes a grip portion (109 A) extending in a cross direction crossing the longitudinal direction of the tool bit, a weight which is housed in the main housing and movable with respect to the main housing, a first crank mechanism which has a first rotation shaft and a first eccentric shaft which is offset from the rotational center of the first rotation shaft, the first crank mechanism being configured to be driven by the motor and drive the driving mechanism (140, 151), and a second crank mechanism which has a second eccentric shaft, a movable plate and a guide pin, which is fixed on the main housing, the second crank mechanism being configured to be driven by the motor and drive the weight via the movable plate such that the weight is relatively moved with respect to the main housing, wherein the second eccentric shaft is fitted onto the first rotation shaft and connected by a connection member wherein the second eccentric shaft is offset from the rotational center of the first rotation shaft, wherein the movable plate comprises an engagement hole engaged with the second eccentric shaft, a first guide hole engaged with the guide pin and push arms for driving the weight, wherein the weight is configured to reduce vibration generated on the main housing during the operation by relatively moving with respect to the main housing, an upper connection part is formed on one end of the grip portion in an extending direction of the grip portion, and a lower connection part is formed on another end of the grip portion in the extending direction of the grip portion, characterized in that the movable plate further comprises a second guide hole, which is engaged with an intermediate shaft of the driving mechanism, wherein the movable plate is guided in the longitudinal direction of the tool bit by the guide holes (255, 254), the handle is configured to be moved with respect to the main housing, each of the upper connection part and the lower connection part are connected to the main housing via a compression coil spring arranged between the main housing and the handle and applying a biasing force on the handle, and the handle is configured to prevent vibration transmission from the main housing to the handle during the operation by relatively moving with respect to the main housing in a state that the biasing force of the compression coil springs is applied on the handle.