An image sensor comprising a plurality of imaging pixels, a plurality of focus detecting pixels in which opening positions of light receiving sections are shifted from those of the imaging pixels, and a plurality of color filters arranged corresponding to the imaging pixels and the focus detecting pixels, wherein first focus detecting pixels in which opening positions are shifted in a first direction are arranged at positions corresponding to first color filters of the imaging pixels, and second focus detecting pixels in which opening positions are shifted in the first direction and which have opening ratios different from those of the first focus detecting pixels are arranged at positions corresponding to the first color filters.