An impact rotation tool including a drive source, an impact force generation unit that generates an impact force for converting power from the drive source to pulsed torque, a shaft that transmits the pulsed torque to a bit used to perform a tightening task, a torque measurement unit that measures torque applied to the shaft as measured torque, a rotation angle measurement unit that measures a rotation angle of the shaft, a tightening torque calculation unit that calculates an angular acceleration from the rotation angle to calculate a tightening torque based on the angular acceleration and the measured torque, and a controller that controls the drive source based on the tightening torque.