An image pickup apparatus a camera 100 includes an image pickup element 105 including a plurality of imaging pixels 106 which perform a photoelectric conversion of an image formed by a light beam from an image pickup optical system and a plurality of focus detection pixels 107 which perform a photoelectric conversion of an image formed by a divided light beam of the light beam, a focus detector 113 which performs a focus detection of the image pickup optical system based on an output of the focus detection pixels 107, an aperture controller 104 which performs a control so that an aperture value of the image pickup optical system is equal to or less than a predetermined value when the focus detector 113 perform the focus detection, and an exposure controller 110 which adjusts an exposure condition in accordance with the aperture value controlled by the aperture controller 104.