There is provided an apparatus including an image sensor of a back-illuminated type using a complementary metal oxide semiconductor (CMOS), including a light receiving unit, formed in a semiconductor substrate, which receives incident light, an anti-reflection film formed on a back-surface side of the semiconductor substrate in which the light receiving unit is formed, and a silicon oxide film, formed on a back-surface side of the anti-reflection film, which has a refractive index lower than a silicon nitride film and has a higher density in a back-surface side than in a front-surface side thereof.