A photoelectric conversion apparatus includes an effective pixel circuit, a reference pixel circuit, a signal output unit, and a comparison unit. The effective pixel circuit includes a photoelectric conversion unit, and is configured to be controlled by using a control line and to output a digital signal based on electric charges generated by the photoelectric conversion unit. The reference pixel circuit includes a holding unit for holding the digital signal. The reference pixel circuit is configured to be controlled by using the control line together with the effective pixel circuit. The signal output unit is configured to output a signal to the holding unit so that a first digital signal with a predetermined value is held by the holding unit. The comparison unit is configured to compare the first signal with the digital signal output from the holding unit controlled to hold the first digital signal.