This paper describes a visual programming interface that enables even inexperienced users to intuitively and easily set automation rules for IoT devices and the usability evaluation. We developed a front-end GUI that allows users to set up rules visually by dragging and dropping blocks with no-code, an “error detection function” that detects and immediately notifies errors, and a “virtual execution function” allows the user to virtually check whether the set rules work as intended. After that, we conducted a usability evaluation experiment to compare the proposed UI with the Node-RED’s UI in terms of operation time, accuracy, and subjective satisfaction. The results show that the proposed UI was significantly more effective in reducing operation time and was equivalent to the Node-RED’s UI in terms of accuracy of operation, and that the proposed UI was highly evaluated in terms of ease of use and recommendation intention.