A substrate for an optical device comprising a base layer; and a plurality of spacers present on the base layer, wherein three, four or six spacers of the plurality of spacers are randomly selected, provided that when the selected spacers have been selected to form a triangle, a quadrangle or a hexagon, which is a closed figure, that other spacers are not present therein, the spacers are disposed so that at least one of the lengths of the sides in the triangle, the quadrangle or the hexagon differs, characterized in that when a normal pitch of the plurality of spacers is P, a standard deviation of the numbers of the spacers in a square region having 10P as one side length is 2 or less, wherein the normal pitch is a distance between the centers of adjacent spacers in a state where the plurality of spacers, in actuality, irregularly disposed on the base layer are placed so that all of the spacers are virtually disposed at the same pitch in consideration of the number of the spacers and the area of the base layer, wherein the maximum length of the lengths of the sides in the triangular, the quadrangle or the hexagon is 600 μm or less, wherein a ratio of the standard deviation to an average number of spacers in said square region is 0.005 to 0.1, wherein the plurality of spacers is arranged such that a normalized area of a spacing normal distribution diagram of the plurality of spacers below half maximum height is in a range of 0.6 to 0.75 and a half height width (FWHM) in the spacing normal distribution diagram is 50 μm to 1000 μm, and wherein the spacing normal distribution diagram is a distribution diagram showing the pitch between the spacers as the X-axis and the ratio of the spacers having the relevant pitch among all the spacers as the Y-axis, where the ratio of the spacers is a ratio obtained when the number of the entire spacer has been assumed to be 1. wherein three, four or six spacers of the plurality of spacers are randomly selected, provided that when the selected spacers have been selected to form a triangle, a quadrangle or a hexagon, which is a closed figure, that other spacers are not present therein, the spacers are disposed so that at least one of the lengths of the sides in the triangle, the quadrangle or the hexagon differs, characterized in that when a normal pitch of the plurality of spacers is P, a standard deviation of the numbers of the spacers in a square region having 10P as one side length is 2 or less, wherein the normal pitch is a distance between the centers of adjacent spacers in a state where the plurality of spacers, in actuality, irregularly disposed on the base layer are placed so that all of the spacers are virtually disposed at the same pitch in consideration of the number of the spacers and the area of the base layer, wherein the maximum length of the lengths of the sides in the triangular, the quadrangle or the hexagon is 600 μm or less, wherein a ratio of the standard deviation to an average number of spacers in said square region is 0.005 to 0.1, wherein the plurality of spacers is arranged such that a normalized area of a spacing normal distribution diagram of the plurality of spacers below half maximum height is in a range of 0.6 to 0.75 and a half height width (FWHM) in the spacing normal distribution diagram is 50 μm to 1000 μm, and wherein the spacing normal distribution diagram is a distribution diagram showing the pitch between the spacers as the X-axis and the ratio of the spacers having the relevant pitch among all the spacers as the Y-axis, where the ratio of the spacers is a ratio obtained when the number of the entire spacer has been assumed to be 1.