The endoscopic diagnosis system comprises an image sensor that receives reflected light from a subject illuminated with white light and first narrowband light to acquire a narrowband light image for blood vessel observation in a narrowband light observation mode, and receives reflected light from the subject illuminated with second narrowband light to acquire a narrowband light image for oxygen saturation level observation in an oxygen saturation level observation mode a controller that controls such that the narrowband light images for blood vessel observation and oxygen saturation level observation are acquired alternately an image processor that generates an oxygen saturation level image based on the narrowband light images for blood vessel observation and oxygen saturation level observation and a display unit that simultaneously displays the narrowband light image for blood vessel observation and the oxygen saturation level image.
