An image sensor includes a plurality of pixels. Each of the plurality of pixels includes a photodetector that includes a photoelectric conversion element that outputs a detection signal in response to light incident thereon, a comparator that compares the detection signal of the photodetector with a ramp signal and outputs a comparison signal in response thereto, a plurality of first memory cells that store a first counting value corresponding to a first voltage level of the detection signal using the comparison signal of the comparator and output the first counting value through a plurality of transmission lines, and a plurality of second memory cells that store a second counting value corresponding to a second voltage level of the detection signal using the comparison signal of the comparator and output the second counting value through the plurality of transmission lines.