Smart manufacturing can be referred as an important consequence of Fourth Industrial Revolution. With the advent of this revolution, manufacturing companies must use numerous new technologies to become smart. According to these new technologies, companies face multifaceted challenges. The Internet of Things (IoT) technology is one of the achievements of Industry 4.0, which plays an important role in the implementation of smart manufacturing. IoT using in smart manufacturing is called Internet of Manufacturing Things (IoMT Like other technologies, IoMT has its own challenges. Therefore, manufacturing organizations must be able to identify these challenges and concentrate on them based on their priority. In this study, by reviewing the literature, the challenges of using the Internet of Things in smart manufacturing were identified. Then Interpretive Structural Modeling (ISM) technique was used to prioritize challenges in the automotive industry. Based on the research findings, the challenges were classified into three levels. This leveling provides a suitable model for automotive industry managers to be able to prioritize their strategies and actions accordingly..