A photoelectric conversion apparatus comprising: a pixel array; a signal line; a processing circuit; a switch for controlling conduction between the signal line and an input node of the processing circuit; and a control unit. The control unit performs a first transition in which, after resetting of the processing circuit, the switch is transitioned to an OFF state and then, during a period after the floating diffusion is reset during which the pixel signals are read out of the pixels into the signal line, the switch is transitioned at least from the OFF state to an ON state; keeps the switch in the OFF state during a period during which the transfer transistor is performing the transfer; and performs a second transition in which, after the transfer, the switch is transitioned from the OFF state to the ON state.