It is intended to provide an imaging apparatus that enables proper exposure of phase difference detection pixels and thereby makes it possible to perform phase difference autofocusing with high accuracy. A system control unit 11 selects phase difference detection pixels from phase difference detection pixels 51R and 51L existing in a selected phase difference detection area 52 according to a position of the selected phase difference detection area 52 in a row direction X, and determines exposure conditions based on output signals of the selected phase difference detection pixels. A defocus amount calculation unit 19 calculates a defocus amount using output signals of the phase difference detection pixels 51R and 51L existing in the selected phase difference detection area 52 that are part of a shot image signal produced by shooting that is performed by an imaging device 5 under the exposure conditions determined by the exposure determining unit 11.