1. A solid-state imaging device, comprising: a light-receiving portion, where a photoelectric conversion is carried out, formed in a semiconductor substrate; an optical filter layer directly formed on or formed through another layer on the surface of the semiconductor substrate in which the light-receiving portion is formed; and quantum dots having substantially equal diameters formed in the optical filter layer, wherein the quantum dots have higher refractive indexes than the refractive index of the optical filter layer in which the quantum dots are embedded.