Based on a future development scenario of CO2 fixation technology, the present study was made in order to develop models which can predict Japan`s energy supply/demand structure as well as the effective decrease in CO2 emission. In fiscal 1992, the scenario was analyzed by case study through designing supply/demand structure from fiscal 1990 through 2030 and pigeonholing data on the premised conditions for those models. The comparison items were supply, system cost, CO2 emission, power required to be generated and energy demand. The scenarios on which the comparison was focused were supply/demand structure, CO2 levy, new energy introduction, CO2 emission control and CO2 fixation. Each of the above items was compared and analyzed from five viewpoints. Judging from the result of the present study, the mathematical model was developed which can analyze the influence of change in each of the different energy supply/demand-related conditions on the energy supply/demand and CO2 emission. 59 figs., 24 tabs.