To provide an automated screwing machine correctly determining the quality of a screwing amount of a screw.

A screw S pressed by a bit 63 moving together with a driver tool 6 abuts on a workpiece to detect that a prescribed moving resistance has acted on the bit 63, and a moving amount of the bit 63 from this position to a screwing completion position is measured. While measuring the moving amount of the bit 63, a moving amount of the bit 63 different from the moving amount at the time of screwing is detected, correction of excluding this amount from the measured moving amount is performed, and the corrected moving amount is compared with a reference moving amount set in advance, to determine the quality of the screwing amount.