A light source apparatus 40 includes: LEDs 42 to 45, each of which emits illumination light of a different color for illuminating an object； an LED driving section 46 that generates driving currents for driving the LEDs 42 to 45； optical sensors 42b to 45b, each of which detects an illuminance value of the illumination light of each color from the LEDs 42 to 45； a memory 41a that stores, as a table 41b, a predetermined range of illuminance values corresponding to driving currents at a time of normal light-emitting of the LEDs 42 to 45； a control section 41 that determines whether or not an illuminance value of any of the LEDs 42 to 45 detected by the optical sensors 42b to 45b is an illuminance value within the predetermined range corresponding to the driving currents, the control section being configured to detect, when determining that the illuminance value of any of the LEDs 42 to 45 is not an illuminance value within the predetermined range, a result of the determination as abnormality in any of the optical sensors 42b to 45b or as abnormality in any of the LEDs 42 to 45.
