<p>A power tool includes a control unit (23) that controls a gear shift actuator (27) to increase the speed reduction ratio of the power transmission unit (22) as the battery voltage detected by the voltage sensor (S) becomes less than or equal to a predetermined voltage when the speed reduction ratio of the power transmission unit (22) is low. By increasing the speed reduction ratio in this manner, the influence of the internal resistance of a battery pack (12) may be reduced. This allows for the power tool may to be continuously used and improves the operability. Further, the control unit (23) stops driving the motor (21) as the battery voltage of the battery (12) detected by the voltage sensor (S) becomes less than or equal to a predetermined voltage when the speed reduction ratio of the power transmission unit (22) is relatively high.</p>
