An auxiliary excitation light source unit 50 is a portable one having a size capable of being held by one hand. The auxiliary excitation light source unit 50 includes an auxiliary excitation light source 51 including a high-power LED in a casing 57. The auxiliary excitation light source 51 emits near-infrared light that is excitation light adapted for exciting indocyanine green and whose wavelength is 760 nm. In front of the auxiliary excitation light source 51, a lowpass filter 53 for blocking light having a wavelength corresponding to the wavelength of fluorescence emitted from indocyanine green is disposed.
