PROBLEM TO BE SOLVED: To easily select a suitable observation mode corresponding to observation conditions.SOLUTION: A light source device 13 is provided with a broadband light source 30 that emits a broadband light beam BB, a blue LD 31 that emits a B-narrowband light beam Bn, and a light composing unit 32 for composing the broadband light beam BB and the B-narrowband light beam Bn. A CPU 54 of a processor device 12 is provided with an observation condition identifying unit 69 for identifying observation conditions including the kind of a part to be observed and whether or not enlarged observation is carried out. Based on the identification result of the observation condition identifying unit 69, the CPU 54 selects a suitable observation mode suitable under the previously identified observation conditions from a plurality of observation modes. The CPU 54 causes a monitor 14 to display a GUI image 62 showing the result of selection of the suitable observation mode, together with an observed image. In this way, it is possible to easily select the suitable observation mode corresponding to the observation conditions.
