In a continuous screw tightening machine with washer stacking supply mechanism, in conjunction with retreating of a tightening machine, a washer is placed on a seat surface portion of a washer feeding body of a washer sequential supply mechanism and reliably supplied to a tightening possible position one by one and the one screw is supplied by a screw sequential supply mechanism between the washer and a bit so as to be in concentric arrangement, in conjunction with advancing of the tightening machine, the washer sequential supply mechanism is set to a feeding preparation attitude of the subsequent washer, and the screw sequential supply mechanism is constituted to be set to a feeding preparation attitude of the subsequent screw, and the screw is tightened and fixed together with the washer at the tightening target spot by rotation/driving of the bit advanced to the tightening possible position by a driving machine.