A signal processing method comprises: applying white balance correction to R (red), G (green), and B (blue) color signals output from a solid-state image pickup element so as to form white-balance corrected R, G, and B color signals; comparing levels of the white-balance corrected R, G, and B color signals with each other; correcting the level of the white-balance corrected G signal to coincide with a lower one of the levels of the white-balance corrected R and B color signals in the case where both of the levels of the white-balance corrected R and B signals are higher than the level of the white-balance corrected G signal when the G color signal is saturated; and outputting the white-balance corrected R, G, and B color signals as image signals.