PROBLEM TO BE SOLVED: To easily acquire an oxygen saturation image without changing design of the whole endoscope system.SOLUTION: An endoscope device 12 sequentially emits B light, G light and R light to a specimen and uses a measuring probe 24 to receive light reflected from the specimen. With respect to the B light out of the light received by the measuring probe 24, its band is limited by a BPF 100 to a first wavelength band where oxyhemoglobin differs from deoxyhemoglobin in an absorption coefficient, and the other G light and R light penetrate as they are without using the BPF 100 to limit their bands. A blue signal B, a green signal G and a red signal R for three colors are obtained by using a sub imaging element 101 to sequentially image Bn light obtained by limiting the band of the B light to the first wavelength band, the G light and the R light. An oxygen saturation image obtained by imaging an oxygen saturation of bloodstream hemoglobin is generated on the basis of the three colored image signals.
