An illumination system includes an excitation light source that emits excitation light, a phosphor unit that converts the excitation light emitted from the excitation light source into fluorescence to emit the fluorescence toward an illuminated object and a light source device including the excitation light source and the phosphor unit. The illumination system further includes a state confirming device that confirms a state of the light source device based on the state of the phosphor unit when connected to the light source device and the phosphor unit emits the fluorescence.