An optical absorber includes a first light-absorbing body which receives light incident from an entrance aperture and partially absorbs and reflects the incident light, and a second light-absorbing body which partially absorbs the incident light reflected by the first light-absorbing body and partially reflects the incident light toward the first light-absorbing body. The reflectance and light resistance of the first light-absorbing body are set higher than the reflectance and light resistance, respectively, of the second light-absorbing body.