A seismic isolation apparatus which has a composite multilayered member comprising a plurality of hard plates having rigidity and a plurality of soft plates having viscoelastic property which are arranged to form alternating layers between an upper flange and a lower flange; and satisfies the condition that the proper vibration to the horizontal direction of the seismic isolation apparatus which is represented by f H and obtained by the equation f H =1/2p√K H M wherein K H represents a spring constant of the seismic isolation apparatus to the horizontal direction, M represents mass of a structure mounted on the seismic isolation apparatus, and f H has a value in the range of: 0.1 Hz≦f H ≦2 Hz when the displacement of the seismic isolation apparatus in the horizontal direction is 2 mm or less, 0.1 Hz≦f H ≦0.8 Hz when the displacement of the seismic isolation apparatus in the horizontal direction is equal to 100% shearing strain, and 0.9 Hz≦f H when deformation in terms of shearing strain is relaxed by 10% from the maximum deformation in measurement of a hysteresis loop of the seismic isolation apparatus. The seismic isolation apparatus has the function of seismic isolation, prevention of shake by wind, and isolation of traffic vibration and is advantageously used for structures having a light weight, such as single family houses.