A target is irradiated in a time-shared manner with a visible-light-range illumination light source and an infrared laser beam for Raman scattering, and a target image is formed with an image-capturing lens on a CIGS image sensor provided with a visible-light-range filter, a narrow-band infrared filter for Raman-scattered light measurement, and a near-band reference narrow-band infrared filter that does not let Raman-scattered light pass through. In a preliminary measurement, a plurality of normal sections are measured and averaged, and by using the same as a reference, an actual measurement of Raman scattering is performed. In displaying a visible-light image with the CIGS image sensor, superimposed display is performed to specify sections where Raman scattering is detected, and superimposed display positions are corrected in association with focusing and zooming. The displaying of the visible-light image is continued even during the detection of Raman scattering.