A simple diffraction grating spectrometer is successfully utilized to distinguish the similar red colored sediments obstained from both of cancer and non-cancer urine reactions caused by the the previous developed reagent for the cancer diagnosis by examining their spectral absorption bands in order to improve its sensitivity and specficity. It is found that the cancer and non-cancer absorp- tion band regions lie between 4250 A and 4750 A and between 5250 A and 5400 A, respectively.