An image capturing apparatus comprises: an image sensor including a plurality of pixels each having a microlens and a plurality of photoelectric conversion means, and defective pixel detection means for detecting defective photoelectric conversion means from among the plurality of photoelectric conversion means, wherein the defective pixel detection means determines defective photoelectric conversion means by comparing an output signal output from photoelectric conversion means of a subject, sequentially taken from the plurality of photoelectric conversion means, for detection with first signals from photoelectric conversion means included in pixels neighboring the pixel including the photoelectric conversion means of the subject for detection, each position of the photoelectric conversion means included in the neighboring pixels corresponding to a position of the photoelectric conversion means of the subject for detection with respect to the microlens.