For increasing a dynamic range, and for signal processing according the gain of an amplifying unit, an imaging apparatus comprises a pixel configured to generate a pixel signal by photoelectric conversion, an amplifying unit amplifying the pixel signal generated by the pixel using a plurality of gains and outputting a plurality of pixel signals corresponding to the plurality of gains, a synthesizing unit selecting one of the plurality of pixel signals output by the amplifying unit in accordance with the size of the pixel signal output by the amplifying unit and outputting a signal based on the selected pixel signal, and a signal processing unit processing the signal output by the synthesizing unit in accordance with the gain of the amplifying unit corresponding to the pixel signal selected by the synthesizing unit.