A novel benzoxazine derivative, 9,10-bis(6-ethynyl-3-pheny1-3,4-dihydro-1,3-benzoxazine)anthracene (1a), was synthesized by the Sonogashira-Hagihara coupling reaction of 9,10-dibromoanthracene and 6-ethynyl-3-phenyl-3,4-dihydro-1,3-benzoxazine. A CH2Cl2 solution of 1a luminesced with a high quantum yield (Phi = 81%). Compound 1a afforded solventinsoluble cross-linked polybenzoxazine 1b by the bulk polymerization at 250 degrees C. Solution polymerization of a dilute solution of 1a at 200 degrees C afforded solvent-soluble samples, accompanied by a decrease of photoluminescence intensity. The weight loss values of 1a and 1b were 81 and 87%, respectively, under nitrogen at 500 degrees C. We believe that the present study will lead to thermally stable curing resins whose degree of curing can be estimated with the naked eye by observing the decrease of photoluminescence.