A cancer-related substance in blood or a biological sample can be detected in a selective manner, so it becomes possible to determine the occurrence of cancer by observation of fluorescent image of a crystal of the censor related substance or a coagulated state of the crystal on a plasmonic chip. In addition, the state of chemical modification of a histone tail can be determined by a Raman spectrum analysis. Furthermore, the location of the cancer-related substance aggregated on a substrate cannot be determined with naked eyes. Then, as a second aspect of the present invention, a method for diagnosing a cancer disease is provided, said method being characterized by firstly identifying the location of the region of a crystal by observing fluorescent image on a microscope, and then irradiating the crystal, with laser beam to analyze with respect to the chemical modification of a histone tail and a remodeling factor.