SHIELDED ROOM MONITORING SYSTEM

PROBLEM TO BE SOLVED: To solve the following problem: in a shielded room monitoring system for normally monitoring electromagnetic shield performance with respect to a building provided with a wide shielded room, such as a general office, even when one transmitter is installed as conventional, transmission radio wave does not reach all areas in the room and, since a plurality of receivers are arranged outdoors, away from the transmitter, they are influenced by radio shielding objects, such as a metallic locker or shelf and disturbance electromagnetic radiation.SOLUTION: Monitoring parts are categorized into a general monitoring part, such as a shield wall 1, and an intensive monitoring part, such as a shield door 2, different frequencies are used, and time-division is performed, and the parts are monitored successively. A plurality of reception antennas 6, 7 arranged in a roof-space near the monitoring parts indoors, are excluded from maintenance objects, and receivers 8, 9 separate from the respective reception antennas 6, 7 are integrated as one every frequency. The respective transmitters are arranged in the roof-space near the respective monitoring parts opposite to the respective reception antennas across the shield wall.