Cost/benefit analysis is considered to be one of the key factors to evaluate government-funded R&D projects, while strong public expectation is paid in the context of intensifying Japan's industrial competitiveness. We made a study on cost/benefit analysis taking one national R&D project as a case, by evaluating the number of patents, market share of the product incorporating the patents, and contribution of governmental bund to such product in qualitative and quantitative ways, as well as its background of the success.