Various kinds of s-triazolo [2, 3-α] pyrimidine derivatives containing methyl group at 2-, 5-, and 7-positions were synthesized and the condensation of these compound with benzaldehyde was investigated. Five kinds of monostyryl derivatives and two kinds of distyryl derivatives were obtained. The structure of these styryl derivatives was confirmed by chemical methods and ultraviolet spectral measurement, and it was clarified that the methyl groups at 5- and 7-positions are active while that at 2-position was not active.