A pixel includes photoelectric conversion elements for generating charges through photoelectric conversion and storing the generated charges in a storing period, transfer elements for transferring the stored charges, an output node to which the charges stored in the photoelectric conversion elements are transferred through the transfer elements, an output buffer part for converting the charges in the output node into a voltage signal at a level determined by the amount of the charges, and a comparator for performing a comparing operation of comparing the voltage signal from the output buffer part against a referential voltage and outputting a digital comparison result signal. The comparator performs, under control of a reading part, the comparing operation on read-out signals read in at least two different modes through different sequences of operations for reading performed on charges stored in the different photoelectric conversion elements.