PURPOSE: To be adapted to a large work material as well at a small cost by arranging rotary shafts at an acute angle with each other.

CONSTITUTION: A first rotary shaft 21 and a second rotary shaft 22 form the acute angle 27 with each other and the focus 14 of a lens 13 is present at the intersection point. Thus, the position is not changed by rotation with the rotary shafts 21 and 22 as a center and the maximum inclination to the rotary shaft 21 of a laser beam abutted to the focus 14 becomes the double of the angle 27. That is, since the inclination is rotated without being obstructed with the shaft 21 as the center, it is adjusted for any azimuth angles. Thus, the inclination to the laser beam 15 made incident to a plane mirror 28 is kept without being changed and the different movement of an optical member is not generated at all other than rotary movement with the rotary shafts 21 and 22 as the center. Thus, mechanical waste is reduced and a structure is not related to the size of a material to be worked.