A solar cell of an embodiment includes a p-electrode, an n-electrode, a p-type light-absorbing layer located between the p-electrode and the n-electrode and mainly containing a cuprous oxide, and a first n-type layer which is located between the p-type light-absorbing layer and the n-electrode, which mainly contains a compound represented by Gax1M1x2M2x3M3x4M4x5Ox6, the M1 being Hf and/or Zr, the M2 being one or more selected from the group consisting of In, Ti, and Zn, the M3 being Al and/or B, the M4 is one or more selected from the group consisting of Sn, Si, and Ge, the x1, the x2, and the x6 being more than 0, the x3, the x4, and the x5 being 0 or more, and the x6 when a sum of the x1, the x2, the x3, the x4, and the x5 is 2 being 3.0 or more and 3.8 or less.