PURPOSE: To simplify a working device, in which the buckling of a work is not developed and the attachment/detachment of the work is simple, in the case of partially thickening without developing the fold even in a thin metallic pipe.

CONSTITUTION: The work 1 of the metallic pipe is rotated with a motor 14 and a compression is applied in the axial direction with a hydraulic cylinder 12. Laser beam 17 from a laser beam generator 16 is converged with a lens 16 and irradiates the outer periphery of the work 1. The work 1 is concentrically heated to the width B having the same degree as the pipe thickness (t) and compressed and thickened. The laser beam 17 is shifted in the arrow mark A direction to thicken the work over to the prescribed width.