<p>Disclosed is a solar cell which is provided with: a transparent electrode (2) formed as an n-type semiconductor; a plurality of carbon nanotubes (3), which are disposed parallel to each other and perpendicular to the lower surface of the transparent electrode (2), on the lower surface of the transparent electrode; and metal electrodes (4) disposed on the lower surfaces of the carbon nanotubes (3), said lower surfaces being on the reverse side of the transparent electrode (2). The diameters of the carbon nanotubes (3) disposed parallel to each other are gradually changed from one side toward the other side, and each of the carbon nanotubes (3) is formed as a p-type semiconductor by being doped with group III atoms.</p>
