A photoelectric conversion apparatus in which a plurality of pixel blocks, each pixel block includes a plurality of first pixels, a plurality of event detection pixels, a determination unit configured to perform event detection, and an interface unit configured to output signals from the plurality of first pixels in accordance with the event detection are arranged. Each of the plurality of event detection pixels includes a first event detection unit configured to output a signal in accordance with incident light, and a first counter unit configured to count signals output from the first event detection unit per a first unit time. The determination unit performs the event detection based on a sum of outputs from the first counter units of the plurality of event detection pixels.