A photoelectric conversion device includes a first cell including a photoelectric conversion layer, a second cell over the first cell including a photoelectric conversion layer formed of a material having a wider band gap than that of the first cell, first and second electrodes under a surface of the first cell which is opposite to the second cell, and a third electrode over a surface of the second cell which is opposite to the first cell. The first and second cells each include a p-n or p-i-n junction, the first and second cells are in contact with each other and a p-n junction is formed in a contact portion therebetween, the first cell is electrically connected to the first and second electrodes to form a back contact structure, and the second cell is electrically connected to the third electrode.