For developing the teaching materials of green chemistry at the students' laboratories in secondary schools, the possibility of green chemical improvement of the synthesis methods of acetylsalicylic acid was investigated by applying the microwave irradiation as the energy source of the synthetic reaction. Through examining the heating characteristics of the reactants by microwave, it was revealed that the application of the microwave irradiation is useful to reduce the amount of a reactant component and the experimental duration. On the basis of such fundamental research on the synthetic condition, a detailed experimental procedure was proposed for applying the improved synthetic method to students' laboratory. In addition, the proposed method was applied to the practice for the green chemistry education at a high school. By comparing the present synthetic method of acetylsalicylic acid with the conventional one, students could become aware of the green chemical effects of the present synthetic method. It is highly expected that the students' understanding on the significance of chemistry for realizing the society which makes sustainable development possible is enhanced through such educational practice on green chemistry.