PURPOSE: To contrive to stabilize pipe manufacturing and to improve productivity by preliminary reducing a diameter through a diameter reducing die, then reducing the inner diameter to be equal to the outer diameter of a grooved plug through a sinking die and then, forming the grooves and reducing the diameter by rolling rolls.

CONSTITUTION: A floating plug 9 and the grooved plug 11 are held previously on a fixed position in the metal pipe 1 through a connecting rod 10. At the time of drawing the pipe, at first, a preliminary diameter reducing work is performed by the diameter reducing die 2 and the floating plug 9. Then, the diameter reducing is performed to reduce the inner diameter of the pipe 1 to equal to about the outer diameter of the grooved plug 11 by the sinking die 8 set on the same axis of the die 2. Succeedingly, the plural rolling rolls 12 revolutes round the outer surface of the pipe 1 in the same number of revolutions of the spindle 3 to form the grooves and to perform diameter reducing by the grooved plug 11. Because the forming of the grooves is performed in the state of equalizing the inner diameter of the pipe 1 with the outer diameter of the plug 11, the manufacture is stabilized and the productivity is improved.