An image capturing apparatus comprises: an image sensor including multiple pixels, each having pupil-divided multiple photoelectric converters, a storage unit that stores the respective pupil-divided image signals, and a control unit, and an operation of adding the image signals on a pixel-by-pixel basis and outputting the resulting signal; a determination unit configured to determine a focus control area, using an image expressed by the image signal output from the image sensor; and a focus control unit configured to carry out focus control according to the phase difference detection method based on the pupil-divided image signals output from the pixels within the focus control area, wherein the control unit switches between an operation of individually outputting the pupil-divided image signals within the focus control area, and an operation of adding and outputting the pupil-divided image signals output from pixels outside of the focus control area on a pixel-by-pixel basis.