A continuous screw tightening machine including a driving machine (4) equipped with a grip handle (2); a tightening machine main body (3) with which a bit (7) for screw tightening is removably connected to the driving machine (4) through a reduction gear and a clutch; and a screw feed mechanism through which the bit (7) is rotatably inserted and which sequentially feeds a screw to the position where a tightening operation is to be carried out by the bit 7. The screw tightening machine also includes a screw feed mechanism main body (6) which is connected to the front of the tightening machine main body (3) so as to be slidable in the longitudinal direction, a screw supply mechanism (110) which continuously supplies a number of single-part screws in sequence to the screw feed mechanism under the force of gravity, and a tip block (12) which is connected to the screw feed mechanism main body, providing a surface to be contacted with an object.