An image capturing apparatus comprises: an image sensor including a pixel region including a plurality of pixel units, arranged in a matrix, each having first and second photoelectric conversion units, and a storage unit provided for each column; and a driving unit configured to drive the image sensor by, for each pixel unit to be read of the plurality of pixel units, exclusively selecting an operation of combining a signal of the first photoelectric conversion unit and a signal of the second photoelectric conversion unit for each pixel unit and outputting the combined signal to the storage unit, an operation of reading a signal from the first photoelectric conversion unit of each pixel unit to the storage unit, or an operation of reading a signal from the second photoelectric conversion unit of each pixel unit to the storage unit.