To improve working performance and reduce cost by employing tapping exclusive to deformed pipes P.

The socket of a deformed pipe P in a raised position is supported on an air-hold chuck 11, and a drilling machine 12 and a tapping machine 13 are arranged outside them. The chuck 11 moves jaws radially to support the socket, and even with a change in pipe diameter, is adaptable via a change in the moving distance. A rotation of the chuck 11 through a given angle can offer dividing, and the orientation of a drill 12a and a tap 13a toward the chuck center can orient a tapped hole along the pipe radius. With one machine 12 moved on a circle concentric with the chuck via a guide 14 to adjust the angle θ that both machines form on the chuck center, rotations of the special pipe each through a set angle locate prepared holes 15a by the drill 12a in sequence in the machining position of the tap 13a.