To provide a substrate for optics provided with a fine-structure product which improves luminous efficiency of an LED while improving internal quantum efficiency IQE by decreasing the number of dislocation defects in a semiconductor layer, a substrate for optics (1) is provided with a fine-structure layer (12) including dots comprised of a plurality of convex portions (13) extending in the direction of from the main surface of a substrate (11) to outside the surface, where the fine-structure layer (12) has a plurality of dot lines (13-1 to 13-N) in which a plurality of dots is arranged with a pitch Py in the first direction in the main surface of the substrate (11), while having the plurality of dot lines in which a plurality of dots is arranged with a pitch Px in the second direction orthogonal to the first direction in the main surface of the substrate (11), one of the pitch Py and the pitch Px is a constant interval of nano-order, while the other one is an inconstant interval of nano-order, or both are inconstant intervals of nano-order.