An image capturing apparatus capable of focus detection includes a sensor including a plurality of pixels, the sensor being capable of changing an accumulation time of the pixels for each of a plurality of regions including the plurality of pixels, an accumulation control unit that, in accordance with a state or a setting of the image capturing apparatus, changes accumulation control of the pixels for each of the plurality of regions, and a defocus computation unit that calculates a defocus amount using signals from the pixels for which accumulation has been controlled by the accumulation control unit.