A diagnostic system comprises a spectral image shooting means that shoots a spectral image within a predetermined wavelength range in a body cavity and obtains spectral image data, an image processing means that obtains the spectral image data and calculates an indicator indicating an area having a high possibility of a diseased portion from the spectral image data, and a monitor on which the indicator is displayed, and wherein the image processing means calculates, as the indicator, a ratio between an accumulated value of intensity values of all spectral images in the predetermined wavelength range and an intensity value of spectral images in a particular wavelength band, for each coordinate in the spectral image.
