A photoelectric conversion device includes a plurality of unit pixels each including a charge holding portion to which charges are transferred from four or more photoelectric conversion units. Sensitivity of each photoelectric conversion unit of a first group to incident light is greater than sensitivity of each photoelectric conversion unit of a second group to the incident light. After charge accumulation is started in all the photoelectric conversion units of the second group, charge accumulation is started in the photoelectric conversion units of the first group. After signals corresponding to charges accumulated in all the photoelectric conversion units of the second group are read out, signals corresponding to charges accumulated in the photoelectric conversion units of the first group are read out.