A photoelectric conversion device includes an avalanche multiplying photodiode, a signal generation unit that includes a control unit configured to control an applied voltage to the photodiode and generates a photon detection pulse based on an output generated by incidence of a photon to the photodiode, and a counter that counts the photon detection pulse output from the signal generation unit, and the counter outputs a setting value detection signal when a count value of the photon detection pulse reaches a predetermined setting value, and in response to receiving the setting value detection signal, the control unit controls the applied voltage to the photodiode so as to stop generation of an avalanche current in the photodiode.