To provide a screw with improved torque transmission efficiency.

A cross recess 12 is formed on a head part 11 of the screw 10. The cross recess 12 is composed of a cross recess body part 13 and a continuous face 15 continuing to the body part. A driver bit 20 is composed of a cross shaped edge part 21 fitted to the cross recess body part 13 and a continuous part 22 continuing to the edge part 21 and fitted to the continuous face 15. The driver bit 20 is fitted in the cross recess 12 and rotated for attaching/detaching the screw 10. As the fitting area S2 of the continuous face 15 and the continuous part 22 is enlarged, the torque of the driver bit 20 can be securely transmitted to the screw 10. The simple constitution improves the torque transmission efficiency to securely carry out attaching/detaching the screw 10.