An imaging device includes an image pick-up device including phase difference detection pixel pairs, each formed from a pair of phase difference detection pixels respectively having their openings eccentrically formed on opposite sides of a main axis of an imaging lens, and imaging pixel pairs; a reading section that reads out signals from the pixels arrayed in the image pick-up device using a rolling shutter method; a first correlation computation section that performs correlation computation on the signals from the phase difference detection pixel pairs; a second correlation computation section that performs correlation computation on the signals from the imaging pixel pairs; a correction section that corrects a result from the first correlation computation section using a result from the second correlation computation section; and a focusing section that performs focus control using the corrected result.