To provide a solar cell for condensing power generation that can secure a conversion factor even if the increase of temperature on a back surface is large.

In a solar cell 16, resistivity R of a base layer 26 is set larger than 0.1 (Ωcm), the thickness (t) of the base layer 26 is set thicker than 0.002 (cm). Furthermore, product of their condensing ratio (c), the resistivity R of the base layer 26, the thickness (t) of the base layer, and product (RΔTtc) of average temperature increase width ΔT of cooling water is set smaller than [-2.9 log(c)+5.1]. In this case, loss caused by increase in series resistance by the temperature increase of the solar cell 16 does not exceed a voltage increase gain by condensing even if other resistance constituents are set to 0, thus keeping a conversion factor ηl high as compared with a case where the back surface of the solar cell 16 is maintained at a fixed temperature or less by a heat sink and the cooling water even if the condensing ration (c) of sun light that is condensed onto a light reception surface 14 is set larger than 10. The average temperature increase width ΔT of cooling water by the cooling of the back surface of a semiconductor substrate 20 is larger than 5 (K).