A light source apparatus includes at least one light-emitter, a driving circuit, an input unit, a temperature control circuit, and an effective light power setting circuit. The driving circuit allows the light-emitter to emit light by applying a driving waveform to the light-emitter. The effective light power setting circuit drives the driving circuit to allow the light-emitter to emit light with a predetermined effective light power, in accordance with a driving condition set by the temperature control circuit. The temperature control circuit controls the light-emitter to be in a predetermined heat generation state by increasing or decreasing a heat generation amount of the light-emitter without changing the predetermined effective light power of the light emitted from the light-emitter by adjusting the driving condition of the light-emitter.