An optical member has: a transparent substrate; and a dielectric multilayer on the transparent substrate formed by stacking a plurality of unit refractive index layers each formed of a high-refractive index layer having a refractive index of 2 or more and a low-refractive index layer having a refractive index of 1.6 or less. In the optical member, a total number of the unit refractive index layers is 15 or more, and a number of the unit refractive index layers satisfying a condition of nHdH/nLdL≧3 is 10 or more, nHdH represents an optical thickness of the high-refractive index layer, and nLdL represents an optical thickness of the low-refractive index layer.