A photoelectrochemical cell (100, 200, 300, 400) comprising: a semiconductor electrode (120, 220, 320, 420) including a conductor (121, 221, 321, 421) and a semiconductor layer (122, 123, 222, 223, 322, 323, 422, 423) comprising a first semiconductor layer (122, 222, 322, 422) and a second semiconductor layer (123, 223, 323, 423), the first semiconductor layer (122, 222, 322, 422) being disposed on the conductor (121, 221, 321, 421) and the second semiconductor layer (123, 223, 323, 423) being disposed on the first semiconductor layer (122, 222, 322, 422); a counter electrode (130, 330, 430) connected electrically to the conductor; an electrolyte (140, 440) in contact with surfaces of the second semiconductor layer (123, 223, 323, 423) and the counter electrode (130, 330, 430); and a container (110, 410) accommodating the semiconductor electrode (120, 220, 320, 420), the counter electrode (130, 330, 430) and the electrolyte (140, 440), characterized in that a band edge level E CS of a conduction band, a band edge level E CS of a valence band, and a Fermi level E FS in the second semiconductor layer (123, 223, 323, 423), and a band edge level E CJ of a conduction band, a band edge level E VJ of a valence band, and a Fermi level E FJ in the first semiconductor layer (122, 222, 322, 422) satisfy, relative to a vacuum level, E CS - E FS > E CJ - E FJ, E FS - Evs < E FJ - E VJ, E CJ > -4.44 eV, and E VS < -5.67 eV, and the Fermi level E FS in the second semiconductor layer (123, 223, 323, 423) and the Fermi level E FJ in the first semiconductor layer (122, 222, 322, 422) satisfy, relative to the vacuum level, -5.67 eV < E FS < -4.44 eV and -5.67 eV < E FJ < -4.44 eV, respectively, characterized in that the first semiconductor layer (122, 222, 322, 422) contains an oxide containing as constituent elements barium, zirconium and indium or barium, zirconium, cerium and indium, and the second semiconductor layer (123, 223, 323, 423) contains an oxide containing as constituent elements barium, zirconium and indium as constituent elements, or barium, zirconium, cerium and indium. a semiconductor electrode (120, 220, 320, 420) including a conductor (121, 221, 321, 421) and a semiconductor layer (122, 123, 222, 223, 322, 323, 422, 423) comprising a first semiconductor layer (122, 222, 322, 422) and a second semiconductor layer (123, 223, 323, 423), the first semiconductor layer (122, 222, 322, 422) being disposed on the conductor (121, 221, 321, 421) and the second semiconductor layer (123, 223, 323, 423) being disposed on the first semiconductor layer (122, 222, 322, 422); a counter electrode (130, 330, 430) connected electrically to the conductor; an electrolyte (140, 440) in contact with surfaces of the second semiconductor layer (123, 223, 323, 423) and the counter electrode (130, 330, 430); and a container (110, 410) accommodating the semiconductor electrode (120, 220, 320, 420), the counter electrode (130, 330, 430) and the electrolyte (140, 440), characterized in that a band edge level E CS of a conduction band, a band edge level E CS of a valence band, and a Fermi level E FS in the second semiconductor layer (123, 223, 323, 423), and a band edge level E CJ of a conduction band, a band edge level E VJ of a valence band, and a Fermi level E FJ in the first semiconductor layer (122, 222, 322, 422) satisfy, relative to a vacuum level, E CS - E FS > E CJ - E FJ, E FS - Evs < E FJ - E VJ, E CJ > -4.44 eV, and E VS < -5.67 eV, and the Fermi level E FS in the second semiconductor layer (123, 223, 323, 423) and the Fermi level E FJ in the first semiconductor layer (122, 222, 322, 422) satisfy, relative to the vacuum level, -5.67 eV < E FS < -4.44 eV and -5.67 eV < E FJ < -4.44 eV, respectively, characterized in that the first semiconductor layer (122, 222, 322, 422) contains an oxide containing as constituent elements barium, zirconium and indium or barium, zirconium, cerium and indium, and the second semiconductor layer (123, 223, 323, 423) contains an oxide containing as constituent elements barium, zirconium and indium as constituent elements, or barium, zirconium, cerium and indium.