To effectively reduce power consumption and improve ability to prevent management information leakage.

When acquiring management information for a manhole 20, a maintenance worker 40 strikes an upper lid 22 of the manhole with a hammer 50, in a specific rhythm pattern for startup. A wireless tag 1 detects a rhythm pattern of the vibration by the striking of the hammer 50 and determines whether the detected rhythm pattern of the vibration is identical to the predetermined rhythm pattern for startup. When the detected rhythm pattern is determined as matching the rhythm pattern for startup, the wireless tag transmits management information, such as, a wireless tag identifier and a result of measurement by a measuring sensor such as immersion detection. A receiving device 30 receives, stores and displays the management information transmitted from the wireless tag 1.