Provided is a photoelectric conversion device including: a pixel configured to generate a first signal in accordance with an incident light by photoelectric conversion; an amplifier unit configured to amplify the first signal to output a second signal; and a comparator unit configured to compare a voltage of the second signal with a voltage of a reference signal. A slope of the ramp waveform included in the reference signal can be switched between a first slope α and a second slope β, the reference voltage used for determining a setting of a gain in the amplifier unit or the comparator unit can be switched between a first reference voltage Vref1 corresponding to the first slope α and a second reference voltage Vref2 corresponding to the second slope β, and α/β≠Vref1/Vref2 is satisfied.