A photoelectric conversion apparatus in which a plurality of pixels are arranged is provided. Each of the plurality of pixels includes an avalanche photodiode arranged between a first potential supply line and a second potential supply line, a first transistor arranged so as to form a current path between the first potential supply line and the avalanche photodiode, and a holding circuit configured to, when avalanche breakdown of the avalanche photodiode has occurred, hold a second potential corresponding a first potential of an electrode of the avalanche photodiode connected to the first transistor. The second potential is supplied to a gate of the first transistor from the holding circuit.