A photoelectric conversion device includes a pixel unit having pixels arranged to form rows and columns, each including a transfer transistor that transfers charge in a photoelectric converter to an output unit, and a pixel control unit that controls the pixels. The pixel control unit is configured to supply a control signal in accordance with an exposure period individually defined for pixel blocks of the pixel unit to pixels of each pixel block and read out, from each pixel, a first signal obtained when the photoelectric converter is in a reset state and a second signal based on charge accumulated in the photoelectric converter during the exposure period. A period excluding both the exposure period and a readout period of the second signal corresponds to a reset period of the photoelectric converter. The transfer transistor is off in a readout period of the first and second signals.