To provide a method of machining a screw capable of precisely machining a female screw by a screw rolling process.

A prepared hole 2 is formed with a punching-out work to a platy metal; then a prepared hole wall is formed with a shaving work, and a press-coining work 6 is applied to the circumference of the broken surface remained in the prepared hole after shaving work, so that the material in the circumference of the prepared hole is press-shifted into the broken surface. Then, this material having the same diameter as the prepared hole diameter can be ensured by inserting under pressing a guide pin having the almost same diameter as the prepared hole diameter. To the prepared hole formed with such way, a screw-work is applied with a rolling tap.