An imaging device includes an image pickup device having an arrangement of photoelectric converting units, the arrangement in which a plurality of pairs of photoelectric converting units are arranged along a predetermined direction, each pair of photoelectric converting units receiving light beams of a subject passing through partial areas in a pair that are lopsided in reverse to each other along the predetermined direction in an exit pupil of a shooting optical system, and a focus detector for performing focus detection of a phase-difference detecting technique according to data obtained from the pair of photoelectric converting units in the arrangement of the photoelectric converting units. The focus detector corrects the data according to a correction amount corresponding to a positional shift amount from the normalized position, and performs focus detection of the phase-difference detecting technique according to the corrected data.