An optical filter includes a substrate and a dielectric multilayer film laid as an outermost layer on at least one major surface of the substrate. The dielectric multilayer film includes a low-refractive index film and a high-refractive index film provided alternately. At least one film selected from the group consisting of the low-refractive index film and the high-refractive index film satisfies the following optical characteristics (i-1) and (i-2A): (i-1) an extinction coefficient k600 at a wavelength of 600 nm is 0.12 or larger; and (i-2A) a minimum extinction coefficient k1530-1570MIN in a wavelength range of 1530 to 1570 nm is 0.01 or smaller; and the optical filter satisfies the following optical characteristic (ii-1A): (ii-1A) light in a wavelength range of 400 to 680 nm is blocked and light in the wavelength range of 1530 to 1570 nm is transmitted.