An image capturing apparatus includes: a focus detection unit configured to perform focus detection based on a phase difference between a plurality of image signals obtained by photo-electrically converting light beams that respectively pass through different partial pupil regions of an imaging optical system; an image blur correction unit configured to correct image blur of an object image by driving an optical member for image blur correction; and a determination unit configured to determine reliability of a focus detection result detected by the focus detection unit based on information regarding a focus detection area with respect to which the focus detection unit performs focus detection, and information regarding vignetting that occurs in light beams that pass through the imaging optical system as a result of the image blur correction unit correcting the image blur.