Provided is an optical substrate provided with a microscopic structure, said optical substrate improving the light-emitting efficiency of LEDs while improving the internal quantum efficiency (IQE) by reducing the number of dislocation defects in a conductor layer. The optical substrate (1) is provided with a microscopic structure (12) containing dots composed of multiple protrusions (13) that extend in the out-of-plane direction from the main surface of a substrate (11). The microscopic structure (12): has multiple rows of dots (13-1 to 13-N) consisting of multiple dots that are arranged at a pitch Py in a first direction within the main surface of the substrate (11); and has multiple rows of dots consisting of multiple dots that are arranged at pitch Px in a second direction that is orthogonal to the first direction within the main surface of the substrate (11). Either one of the pitch Py or the pitch Px is at a regular interval on a nano-order scale, while the other is at an irregular interval on a nano-order scale, or both pitches are at an irregular interval on a nano-order scale.