Recently, there is a growing demand to know con- gestion information on sightseeing spots in real-time to provide a satisfactory tour plan to tourists. Many studies on a congestion estimation have been conducted so far. However, most of them suffer from high deployment/operation costs and/or rely on contributions by users with smartphones/sensors. In this paper, we propose a novel system that estimates congestion of sightseeing spots in real-time without attaching any device to tourists by observing the distribution of per-RSSI intensity occurrences in each time window when beacon signals are periodically sent between BLE (Bluetooth Low Energy) transceivers installed in sightseeing spots. In other words, our system can estimate the congestion degree in sightseeing spots simply by using the property of RSSI intensity which dramatically changes depending on the number of people. Therefore, the proposed system is simple and low cost and can estimate the congestion easily without any special devices attached to tourists. In the demonstration, we show the congestion degree in three levels (low, medium, and high) changing in real-time depending on the number of audience in the demonstration site.