To provide a screwdriver and a screwdriver bit positioning tool capable of easily fitting a screwdriver bit to the head part of a screw.

In this screwdriver bit positioning tool for positioning the tip part of the screwdriver bit to the head part of the screw, the driver bit 5 is concentrically inserted, and a guide collar 2 is slidably installed on the driver bit 5. The guide collar 2 comprises, at its tip inner periphery, a tapered surface 2 allowed to abut on the head part of the screw and diverging toward the tip thereof.