An automatic screw tightening control method, wherein: an electric driver provided with an electric motor, a drive switch for driving this electric motor, and a driver bit coupled to a drive output shaft of the electric motor via a reduction gear mechanism and a clutch mechanism and provided with a switch operating member for operating the drive switch, a clutch operation detection sensor for detecting a clutch operation of the clutch mechanism, an electric motor control circuit for executing driving and stop control of the electric motor, and rotation amount detecting means for detecting a rotation amount of the electric motor, respectively, is used; in a predetermined screw tightening operation by the electric driver, the rotation amount of the electric motor at clutch operation time by the clutch mechanism associated with completion of the screw tightening from screw-tightening start time in the predetermined screw tightening operation is detected (STEP-2) by the rotation amount detecting means, and the detected rotation amount is set (STEP-3) to be a target rotation amount, including a permissive range; and in subsequent predetermined screw tightening operations by the electric driver, it is set that the rotation amount of the electric motor from the screw-tightening start time until the clutch operation time by the clutch mechanism associated with completion of the screw tightening is sequentially detected (STEP-5) by the rotation amount detecting means, and the rotation amount detected at the clutch operation time is compared (STEP-6) with the target rotation amount, including the permissible range, whereby acceptability of the screw tightened state is determined. an electric driver provided with an electric motor, a drive switch for driving this electric motor, and a driver bit coupled to a drive output shaft of the electric motor via a reduction gear mechanism and a clutch mechanism and provided with a switch operating member for operating the drive switch, a clutch operation detection sensor for detecting a clutch operation of the clutch mechanism, an electric motor control circuit for executing driving and stop control of the electric motor, and rotation amount detecting means for detecting a rotation amount of the electric motor, respectively, is used; in a predetermined screw tightening operation by the electric driver, the rotation amount of the electric motor at clutch operation time by the clutch mechanism associated with completion of the screw tightening from screw-tightening start time in the predetermined screw tightening operation is detected (STEP-2) by the rotation amount detecting means, and the detected rotation amount is set (STEP-3) to be a target rotation amount, including a permissive range; and in subsequent predetermined screw tightening operations by the electric driver, it is set that the rotation amount of the electric motor from the screw-tightening start time until the clutch operation time by the clutch mechanism associated with completion of the screw tightening is sequentially detected (STEP-5) by the rotation amount detecting means, and the rotation amount detected at the clutch operation time is compared (STEP-6) with the target rotation amount, including the permissible range, whereby acceptability of the screw tightened state is determined. <EOS>