A photoelectric conversion device according to one embodiment includes: a first substrate including a pixel that includes a photoelectric conversion element; and a second substrate including a first control unit that includes a first signal processing unit configured to process a signal from the pixel, the second substrate being stacked together with the first substrate. The signal from the pixel is output to a second signal processing unit disposed at a position different from a position of the first signal processing unit, a path through which the signal from the pixel is output to the first signal processing unit is different from a path through which the signal from the pixel is output to the second signal processing unit, and the first control unit is configured to control the pixel on the basis of the signal processed by the first signal processing unit.