An impact tool that realizes an ON-lock function with a simple mechanism and makes it possible to switch between activation and deactivation of the ON-lock function with few operation processes is provided. A hammer drill having at least two operating modes including a hammer mode in which an impact force is transmitted to a tool bit whereas a rotational force is not transmitted thereto includes: a motor as a power source; a trigger lever and an ON-lock button that are operated by an operator; a sensor that detects whether a selected operating mode is the hammer mode or not; and a controller that controls the motor based on an operation of the trigger lever and the ON-lock button. When the ON-lock button is operated while the hammer mode is selected, the controller performs ON-lock control to maintain the motor in the operating state even when the trigger lever is not operated.