PROBLEM TO BE SOLVED: To provide a flexible solar battery which is excellent in heat resistance and transparency and has high photoelectric conversion efficiency.SOLUTION: The solar battery includes: a first substrate 1 containing silsesquioxane polymer cured product with at least one type of silsesquioxane shown by equations (A-1) to (A-3) described in a specification taken as a fundamental unit and glass fiber; a cathode 2 which is a transparent conductive film deposited on the first substrate 1; an anode 6 which is a counter electrode of the cathode 2; and a photovoltaic layer sandwiched between the cathode 2 and the anode 6.
