It is an object of this invention to provide the structure of an image sensor capable of efficiently collecting light in the center and in the periphery of an imaging plane. To achieve this object, an image sensor includes a plurality of photoelectric conversion portions, a high refractive index portion having a first portion formed into the shape of a pillar and a taper shape portion whose aperture area increases toward a side close to a photographing lens, and a low refractive index portion placed around the high refractive index portion. Letting x1 be an aperture width on the side at which the aperture area of the taper shape is large, x2 be an aperture width on the side at which the aperture area of the taper shape is small, .theta..degree. be the inclination angle of the taper shape, n1 be the refractive index of the high refractive index portion, n2 be the refractive index of the low refractive index portion, F be the F number of the photographing lens, R be the distance from the center of the optical axis of the photographing lens to the photoelectric conversion portion, and f be the distance from the position of the pupil of the photographing lens to an imaging plane, the high refractive index portion is formed into a shape which satisfies relations represented by 1>x2/x1.gtoreq.(1-tan .theta./tan .theta.')/(1+tan .theta./tan .theta.') and cos .theta.'.gtoreq.n2/n1 where .theta.'=.theta.0'+2.theta. and sin .theta.0'=1/2n1F+R/n1f.