An impact rotary tool includes a motor, an output shaft configured to hold a tip tool and configured to rotate by a motive power of the motor, an impact mechanism configured to perform an impact operation to repeatedly generate, from the motive power of the motor, impact force acting on the output shaft, and a seating detector configured to detect a seating of a fastener component which is a state where the fastener component rotated by the tip tool is just seated on a work target. The seating detector has a plurality of seating detection modes. The impact rotary tool further includes an acquirer configured to acquire information indicative of one seating detection mode selected from the plurality of seating detection modes. The seating detector is configured to detect the seating of the fastener component based on the one seating detection mode indicated by the information acquired by the acquirer.