Pluralities of lens parts 20, 22 are formed on a lens substrate 16 by dry-etching. The lens parts 20 and 22 have same structures, and the lens part 20 includes toroidal lens surfaces S1 and S2 opposing to each other on one principal surface and another principal surface of the substrate 16. Assuming that a cross section in a y-axis direction of a laser beam emitted from a laser active layer in a z-axis direction is long and narrow in an x-axis direction, the lens surface S2 is formed to have a radius of curvature R.sub.21 in the x-axis direction smaller than a radius of curvature R.sub.22 in the y-axis direction, and the lens surface S1 is formed to have a radius of curvature R.sub.11 in the x-axis direction smaller than a radius of curvature R.sub.12 in the y-axis direction.