Cathodoluminescence (CL) properties of various kinds of organic material were investigated for the purpose of staining biological specimens and obtaining CL images. Several kinds of organic light emitting device (OLED) material exhibited CL. The europium complex, Eu(dbm)3(phen), showed the strongest CL signal and was chemically modified for biological staining. However, the CL intensity from the stained biological specimen was too weak to build CL images. We discussed the CL properties of organic materials considering their chemical structure and charge distribution in the molecules.