PROBLEM TO BE SOLVED: To adjust a color tone of an image to be displayed so that mucus or the like does not turn red.SOLUTION: An electronic endoscope system includes: a lighting apparatus 14 for irradiating a biochemical tissue in a body cavity with illumination light containing a plurality of colors a CCD 21 for taking images of the biological tissue under the illumination light, and outputting color signals of each color as imaging signals, while a plurality of color filters are allotted to each pixel an R/G calculating part 60 for calculating a ratio (R/G) of two color signals of two colors out of color signals and a display image generator for generating a display image by allotting the color signals to pixels having colors different from the color filters. A DSP52 for generating a display image wherein a color tone is adjusted in such manner that mucus is adjusted to be a predetermined color when the mucus and blood are discriminated based on a value of the ratio R/G calculated by the R/G calculating part 60 and the mucus is reflected on the display image.
