Conventionally, for a product accompanied by supplies such as a copy machine or a printer, the demand figures relating to the supply which such a main machine consumes have been determined empirically from the transition of the past sales records of the supply, the trends of the market, and a sales scheduled figures of the main machine. Therefore, the forecasted values of the demand figures differ in accordance with the skills or experiences of individuals carrying out the forecasting, and necessarily, the accuracy of the forecasted values deteriorates. Further, a demand forecast method relating to the supplies of a product has not been realized due to the large number of parameters, the complexity of calculation, and the difficulty of a systematic approach for solving problems.In order to overcome the above-described problems, the invention of the present application forecasts consumption figures of a supply for outputting an outputted matter in the future, on the basis of inputted output figures of an outputted matter outputted by a product and sales figures of the supply.