To provide an apparatus for evaluating the effectiveness of base isolation and capable of measuring the magnitude of oscillations which base isolation buildings received from earthquakes etc. and evaluating the effectiveness of base isolation of base isolation bearing devices, an oscillation measuring system for measuring oscillations of each building through the use of the same, and a control system capable of suppressing damage due to oscillations by controlling facilities when the buildings receive large oscillations.

The apparatus 1 for evaluating the effectiveness of base isolation is provided with acceleration sensors 10a and 10b and an arithmetic processing part 11 for determining the difference between detection output of both acceleration sensors 10a and 10b by comparison. One acceleration sensor 10a is installed to the side of foundation ground X to detect the magnitude of oscillations of the foundation ground X, and the other acceleration sensor 10b is installed to the side of a house H to detect the magnitude of oscillations of the house H. The arithmetic processing part 11 computes the difference between the magnitudes of both oscillations. The state of oscillations indicated by operation data of the arithmetic processing part 11 is displayed on a monitoring device 40 of a base unit 4 of an intercom device.