A highly reliable solar cell is achieved which has a high photoelectric conversion efficiency and no aged deterioration. A cell 10 (unit cell) is formed as a unit, comprising: a lower electrode layer 2 (Mo electrode layer) formed on a substrate 1 (substrate); an absorber layer 3 (CIGS absorber layer) which contains copper, indium, gallium, and selenide; a highly resistant buffer layer thin film 4 formed of InS, ZnS, CdS, or the like on the absorber layer 3; and an upper electrode layer 5 (TCO) formed of ZnOAl or the like, and furthermore, a contact electrode section 6 for connecting between the upper electrode layer 5 and the lower electrode layer 2 is formed in order to connect a plurality of unit cells 10 in series. The contact electrode section 6 has, as will be explained later, a Cu/In ratio higher than that of the absorber layer 3, and in other words, has less In contained therein to have a property of p+ (plus) type or a conductor relative to the absorber layer 3 which is a p-type semiconductor.