An image sensor having a plurality of photoelectric conversion elements that receive light and convert the light to electric charges, color filter layers having different spectral characteristics, each being provided corresponding to each of the photoelectric conversion elements, and a partition wall having a lower refractive index than that of the color filter layers provided at the boundary of each color filter layer. The image sensor is formed such that a space of the partition wall on the light exit side is narrower than a space of the partition wall on the light incident side.