Efficiently managing network infrastructures laid in corporate organizations and universities is a crucial task. Making wireless network segments stably running is particularly an expensive and time consuming task. Providing a system for continuously monitoring the wireless network and simply visualizing up-to-date network conditions should be a big help for administrators and even for end users. In this paper, we propose a wireless network visualizer based on signal strength observation using IoT devices and lightweight communication protocol. We describe a concept and an implementation approach of the wireless network visualization system.