Abstract: Reliability of a semiconductor device is improved. A solar battery includes: a solar battery element SB1 including an interface S1; a solar battery element SB2 including an interface S2 facing the interface S1; and a junction layer 120 being in contact with the interface S1 and the interface S2 and having light transmissivity. In this case, the junction layer 120 includes: a plurality of conductive nanoparticles 105 electrically connecting the solar battery element SB1 and the solar battery element SB2; and an adhesive material 116 filling gaps among the plurality of conductive nanoparticles 105. The interface S1 includes: a flat surface FT having concavity/convexity that is equal to or smaller than 2/3 times the minimum thickness of the junction layer 120; and a concave portion DIT having a depth that is equal to or larger than twice the minimum thickness of the junction layer 120 with respect to the flat surface FT.