Abstract: Electricity, gas, water and nuclear power are national infra systems. In other words, when a security problem occurs in the information processing of the SCADA (Supervisory Control and Data Acquisition) system which is the infra facility of the country an immediate threat to the lives of the people occurs and affects the national security. This study improves the cybersecurity vulnerability of the information system managing local waterworks. We design L2 and L3 switches connected to the firewall. We design UTM (Unified Threat Management) equipment for water treatment administrative information processing. We design computer virus vaccine for database and secure network traffic through network management system. Through the operation of CERT/CC (the Computer Emergency Response Team/the Cybersecurity Control Center), it responds to and prevents cyber-attacks such as advanced persistent threat attack, zero-day attack and DdoS (Distributed Denial of Service Attack) attack. We study cybersecurity system of water treatment SCADA system and study safe water treatment SCADA support system.