A photoelectric conversion apparatus includes: a first substrate including an avalanche photodiode; and a second substrate, in which the first substrate and the second substrate are stacked on each other, and further includes: a temperature detection unit arranged in at least one of the first substrate and the second substrate and having an output characteristic depending on a temperature; and a temperature value generating circuit arranged outside the first substrate and configured to convert output from the temperature detection unit into a temperature value signal that is a signal indicating temperature information.