A method executed by a computer includes searching a design subject having similar attribute information from attribute information on a design subject designed in the past and histories of descriptions of improvements based on input information on a design subject; obtaining a description of an improvement on the searched design subject having similar attribute information from the histories, obtaining a design subject the description of an improvement of which has an effect of the improvement, and outputting improved input information, wherein the attribute information contributing to the improvement of the design subject is obtained and reflected in the input information, and the history of the improved input information is stored.