A system and method for providing authentication service for IoT security are disclosed herein. The system for providing authentication service for IoT security includes an Internet of Things (IoT) service server, and an IoT gateway node. The IoT service server supports an IoT communication service in accordance with an IoT communication service policy. The IoT gateway node receives an IoT service request from a terminal attempting to control an IoT device that supports the IoT communication service while operating in conjunction with the IoT service server, identifies whether the terminal attempting to control the IoT device is a normal user based on profile information, collected from the terminal via the IoT service request, via the IoT service server, and performs the security authentication of the IoT device.