An image pickup apparatus, including: a pixel array in which a first row group is to be read in a first mode for reading a signal corresponding to combined electric charges that are obtained by combining electric charges generated by the plurality of photoelectric converters, and a second row group is to be read in a second mode for reading a signal corresponding to electric charges that are generated by any one of the plurality of photoelectric converters; a correction value generating unit configured to generate a first and a second correction value for correcting a signal that is read in the first and the second mode, respectively, a correction unit configured to correct, by using the first correction value, the signal that is read in the first mode, and to correct, by using the second correction value, the signal that is read in the second mode.