The system includes an illuminating unit, an electronic endoscope, a unit for outputting first image data having different wavelength bands from the imaging signal, a unit for producing blood vessel information from the first image data, a unit for setting a given region in an image as reference value region, a unit for calculating a reference value for the blood vessel information based on second image data for a region within a reference value region, a unit for calculating relative value blood vessel information from the difference between the blood vessel information and the reference value blood vessel information, a unit for producing a simulated-color relative value blood vessel information image from the relative value blood vessel information, and a monitor for displaying a relative value blood vessel information image.
