Provided is a semiconductor device including: first signal generation units arranged so as to form rows and columns and corresponding to pixels configured to output a signal in response to incidence of light, each of the first signal generation units being configured to output a first digital signal in response to an output from a corresponding pixel; second signal generation units arranged corresponding to at least a part of the rows and the columns, each of the second signal generation units being configured to output a second digital signal having a predetermined digital value; and a readout unit configured to output a signal based on at least one of the first digital signal and the second digital signal that is output from a selected part of the first signal generation units and the second signal generation units.