As the age of Internet of Things (IoT) has come, national-level cyber security measures should be prepared and concrete implementation plans should be established, so that critical infrastructure can be operated and maintained safely, protected from cyber attacks. In addition, IoT services for such infrastructure should be capable of closely obtaining and processing information in environments experienced by users. To provide reliable IoT services for critical infrastructure utilizing IoT devices, based on an understanding of the vulnerabilities of IoT technology and cutting-edge cyber threats, this paper proposes methods for predicting errors that may occur in physical situations, where things are connected to each other and analyzing and modeling the errors as a functional requirement. In addition to technical measures, security guidelines are presented for individual fields, such as policy, organization, manpower, budget, industry, R&D, and education.