A photothermal power generation device designed to heat an emitter receives a supply of fuel and air, burns the fuel to produce combustion gas, and converts light emitted from the emitter into electric power by means of a photoelectric conversion element. The device is provided with a flow resistance adjusting unit for adjusting a flow resistance of the combustion gas in the emitter in accordance with a state of combustion gas, a combustor fire vent adjusting unit for adjusting the shapes of, or a number of, fire vents formed in the combustor in accordance with a required output, or a discharge state adjusting unit for adjusting a discharge state of exhaust gas in accordance with a state of the combustion gas. This photothermal power generation device provides uniform light-emitting intensity and enhances power generation efficiency.