1. An image sensor that captures an image formed through an optical system and that comprises a plurality of types of imaging pixels with spectral sensitivity characteristics different from one another, two-dimensionally disposed in a Bayer array, wherein: a plurality of focus detection pixel rows are disposed so as to occupy part of the Bayer array and extend along a plurality of directions intersecting each other, each made up with a plurality of focus detection pixels set along one of the plurality of directions, the focus detection pixel rows are used to detect a focusing condition of the optical system; and a focus detection pixel occupying a position at which the focus detection pixel rows intersect is set at a position equivalent to a position of one of a blue pixel and a green pixel in the Bayer array.