Abstract Commercial software companies face many challenges when competing in today’s fast moving and competitive industry environment. Recently, the use of open source software (OSS) has been proposed as a possible way to address those challenges. OSS provides many benefits, including high-quality software and substantial profits. Nevertheless, OSS has not been effectively utilized in real business. The purpose of this paper is to find what affects the utilization of OSS. For this study, we propose a structural equation model (SEM) to analyze the relationships between the quality factors based on ISO/IEC 9126 and OSS utilization. In addition, we suggest an open source software utilization index (OSSUI) based on the proposed SEM. The results provide us with the controllable feedback information to improve user (programmer) satisfaction during OSS utilization.