An imaging device comprising: a plurality of pixels including a first pixel that detects one of a pair of light beams which pass through different pupil regions of a single imaging optical system and a second pixel that detects the other of the pair of light beams, the plurality of pixels being two-dimensionally arranged, wherein a light receiving region of the first pixel deviates from a center of the first pixel in one direction, a light receiving region of the second pixel deviates from a center of the second pixel in a direction opposite to the one direction, characterized in that the plurality of pixels are arranged in a square lattice shape, wherein first pixels which detect light of a first color and first pixels which detect light of a second color are arranged alternately in first rows in the square-lattice-shaped arrangement, second pixels which detect light of a first color and second pixels which detect light of the second color are arranged alternately in second rows in the square-lattice-shaped arrangement vertically adjacent to the first rows and such that first pixels detecting light of the first color in the first rows and second pixels detecting light of the first color in the second rows are aligned in vertical direction between the first row and the second row, first pixels which detect light of a third color and first pixels which detect light of a first color are arranged alternately in third rows in the square-lattice-shaped arrangement vertically adjacent to the second rows such that the first pixels detecting light of the third color in the third rows and the second pixels detecting light of the first color in the second rows are aligned in vertical direction, second pixels which detect light of a third color and second pixels which detect light of a first color are arranged alternately in fourth rows in the square-lattice-shaped arrangement vertically adjacent to the third rows such that the second pixels detecting light of the third color in the fourth rows and the first pixels detecting light of the third color in the third rows are aligned in vertical direction. a plurality of pixels including a first pixel that detects one of a pair of light beams which pass through different pupil regions of a single imaging optical system and a second pixel that detects the other of the pair of light beams, the plurality of pixels being two-dimensionally arranged, wherein a light receiving region of the first pixel deviates from a center of the first pixel in one direction, a light receiving region of the second pixel deviates from a center of the second pixel in a direction opposite to the one direction, characterized in that the plurality of pixels are arranged in a square lattice shape, wherein first pixels which detect light of a first color and first pixels which detect light of a second color are arranged alternately in first rows in the square-lattice-shaped arrangement, second pixels which detect light of a first color and second pixels which detect light of the second color are arranged alternately in second rows in the square-lattice-shaped arrangement vertically adjacent to the first rows and such that first pixels detecting light of the first color in the first rows and second pixels detecting light of the first color in the second rows are aligned in vertical direction between the first row and the second row, first pixels which detect light of a third color and first pixels which detect light of a first color are arranged alternately in third rows in the square-lattice-shaped arrangement vertically adjacent to the second rows such that the first pixels detecting light of the third color in the third rows and the second pixels detecting light of the first color in the second rows are aligned in vertical direction, second pixels which detect light of a third color and second pixels which detect light of a first color are arranged alternately in fourth rows in the square-lattice-shaped arrangement vertically adjacent to the third rows such that the second pixels detecting light of the third color in the fourth rows and the first pixels detecting light of the third color in the third rows are aligned in vertical direction.