An image capturing apparatus is provided with an image sensor that has a first pixel group and a second pixel group, a focus adjustment unit that executes focus adjustment of an imaging lens based on the signal from the second pixel group, a readout unit that has a first thinning and readout mode that thins and reads out signals from the plurality of pixels at a predetermined thinning ratio and thinning phase, and a second thinning and readout mode that thins and reads out signals from the plurality of pixels with a difference in at least one of the thinning ratio and the thinning phase from the first thinning and readout mode, and a selecting unit that selects in which mode to operate the readout means from among the first and second thinning and readout modes in accordance with the state of the image capturing apparatus.