A solid-state image sensor having unit pixel cells arranged in a matrix form, each unit pixel cell having a photoelectric conversion element formed on a semiconductor substrate, a color filter formed on the photoelectric conversion element and a micro-lens formed on the color filter, where a thickness of the color filter is greater in the center than in the periphery. Further, the color filters adjoin in vertical and horizontal directions in the arrangement of the unit pixel cells. A cross-sectional shape of the color filter is, for example, triangular, trapezoidal, convex, lens-shaped or semielliptic.