Cancer diagnosis device contains an endoscope comprising a light pipe used to transmit light beams from respective light sources and an image guide used to observe the flesh of the organism during both diagnosis and treatment. The tip of the endoscope faces toward the focuses where a photosensitive material having an affinity to the focuses of cancer has been absorbed so that a treatment for cancer can be performed by exposing the organism affected by cancer to the laser beam. The attainable the laser beam within a focus is thus increased by the use of the laser beam pulse from a first laser beam pulse source. In addition to the above, the cancer diagnosis device contains a second laser beam pulse source used to transmit a light beam to the focuses through the light pipe for making a diagnosis, a selector used to selectively pick up the light beam from the first laser beam pulse source or the second laser beam pulse source, a spectroscope used to obtain the spectral response from emission of light led through the image guide used for observation from the flesh of the organism where fluorescence occurs, an imaging device used to pick up the spectral response, a graphic display used to graphically display the processed spectra picked up by the imaging device, and a controller used to control emission of light from the second laser beam pulse source and also to make the operation of the imaging device synchronize with the second laser beam pulse source.