A technology roadmap (TRM) links technologies with a company's strategic objectives and so supports acquisition of required technologies in advance of needs. It is a powerful tool for strategic planning and technology management. Because technology is changing rapidly and market competition is fierce, the role of a TRM is becoming increasingly important. To support the role of a TRM, many firms and governments that use roadmapping are becoming interested in reducing costs while retaining objectivity during TRM development. One suggestion to achieve these goals is to use the keyword-based quantitative approach to creating a TRM, but the information provided by the approach is limited because of the characteristics of keyword information. To solve this limitation, this research uses the concept of ‘function’ to support quantitative analysis for developing a TRM. The concept of function can provide information on the uses and purposes of a technology. To represent a function, a subject–action–object structure is commonly used. The suggested approach allows research and development (R&D) managers to extend the views of product and technology during development of a TRM. In addition, by reducing the time required to develop a TRM, the proposed approach supports quick and accurate decision-making by R&D managers.