An image capturing apparatus has an image sensor in which unit pixels each having a plurality of photoelectric conversion portions are arranged in matrix, a readout unit for performing a first readout operation of reading out signals of a portion of the plurality of photoelectric conversion portions and a second readout operation of reading out signals of a greater number of the plurality of photoelectric conversion portions, a switching regulator, and a frequency controller for controlling a switching frequency of the switching regulator. The frequency controller controls the switching frequency such that the phase of the switching frequency satisfies predetermined relationship, with respect to a timing for reading out noise signals, a timing for reading out signals by the first readout operation, and a timing for reading out signals by the second readout operation.