A light source apparatus includes a cooling device configured to be able to cool a semiconductor light-emitting device, a light-emitting device drive section that supplies a semiconductor light-emitting device drive signal to the semiconductor light-emitting device, a cooling device drive section that supplies a cooling device drive signal to the cooling device, a semiconductor light-emitting device drive control section that sets a duty ratio of the semiconductor light-emitting device drive signal and controls an amount of light emission of the semiconductor light-emitting device, and a cooling device drive control section that generates the cooling device drive signal having a same duty ratio as the duty ratio of the semiconductor light-emitting device drive signal and having timing synchronized with the semiconductor light-emitting device drive signal and adjusts a signal level of the cooling device drive signal based on a measurement result of a temperature of the semiconductor light-emitting device.