An image pickup apparatus for simultaneously realizing a phase difference AF and a contrast AF decides a shift amount of an image signal corresponding to a focus evaluation position every exit pupil area, generates an image corresponding to an image plane position by executing an arithmetic operation processing based on the decided shift amount to the image signal, calculates an evaluation value of a contrast of the generated image, and calculates an evaluation value of a correlation between the images corresponding to the different exit pupil areas in the generated image.