When chemical process conditions and chemical species are input on a spreadsheet software (1), a chemical model is selected according to the chemical species by a software (4, 5, 6) different from the spreadsheet software (1), thermodynamic property data for the chemical model is generated, and a chemical equilibrium is evaluated based on this data. The chemical equilibrium is simulated on the spreadsheet software (1) based on this evaluation result, and the simulation result is displayed on the spreadsheet software (1).