To provide a lighting system for improving the accuracy of temperature control of an optical member transmitting illumination light without blocking an optical path of the illumination light emitted by a light source.

The lighting system (100) includes a light source section (140) for emitting illumination light, a light-transmitting member (160) for transmitting the illumination light emitted from the light source section, a moving mechanism (150) for moving the light source section in the optical axis direction of the illumination light with respect to the light-transmitting member, a measurement unit (190) having a temperature sensor that receives radiation light radiated from the light-transmitting member and measures the temperature of the light-transmitting member based on the amount of the received light, and a measurement unit movable section (170) for displacing at least a portion of the measurement unit in response to the presence position of the light source section in the moving direction so that the radiation light radiated from the light-transmitting member enters the temperature sensor regardless of the presence position of the light source section in the moving direction.