An imaging apparatus includes an image pickup device that includes a first pixel group configured to photoelectrically convert an object image formed by a luminous flux from an imaging optical system, and a second pixel group which includes a plurality of pixels configured to photoelectrically convert a split pair of the luminous flux from the imaging optical system and a detecting unit configured to implement a first detection control that changes an imaging state of the image pickup device while detecting a contrast of the object image based on an output of the second pixel group, and then a second detection control that changes the imaging state of the image pickup device while detecting the contrast of the object image based on an output of the first pixel group.