To reduce the number of shafts by replacing a kind of head with some kinds of shafts, to save a management space of tools such as drivers and reduce cost in a factory, etc.

A driver shaft has the head having a structure engaged to the head of a screw or a nut, etc., at the tip of the shaft. The driver shaft has a structure in which the head 11 and the shaft 12 are divided, and each shaft 12(1) to 12(n) having a different length can be replaced with the head 11 via an attaching/detaching mechanism 20. The attaching/detaching mechanism 20 has a fitting structure capable of transmitting torque.