PROBLEM TO BE SOLVED: To implement both switching of an irradiation lights wavelength band and acquisition of an observation image having higher quality.SOLUTION: There is provided a lighting device comprising: a first light source unit for emitting white light a second light source unit for emitting laser light with at least one predetermined wavelength band included in a wavelength band of the white light and a multiplexing member for multiplexing the white light and the laser light. The multiplexing member includes: a polarization conversion element that is at least arranged on a light path of light having random polarization out of the white light and laser light to convert a polarization direction of incident light to a predetermined direction and a polarization beam splitter onto which light having passed through the polarization conversion element is incident. The polarization beam splitter multiplexes the white light and the laser light whose polarization directions are orthogonal to each other by the polarization conversion element.SELECTED DRAWING: Figure 1
