PURPOSE: To effectively prevent transmission of vibration over a wide range by variably setting a spring constant and damping coefficient of a device by a compact structure without providing a valve unit or the like.

CONSTITUTION: A rubber elastic material wall 1 is spread to open downward into an umbrella shape to support a vibrating unit to a top surface. A pair of spaces 11, 12 are formed in a wall adjacent to an internal surface in a position of diametric directional symmetry of the rubber elastic material wall 1 and sealed with electric viscous fluid to form acting chambers C, D. A fluid circulating path F2, in which an electric field forming electrode film is formed on a path wall, is provided by connecting the acting chambers C, D, and an acting subchamber E with a rubber film 4 serving as a chamber wall is provided to connect the fluid circulating path F2 to branch. When an electrode is electrified, an electric field is generated in the fluid circulating path F2 to make the electric viscous fluid difficult to circulate. When vibration is input, the electric viscous fluid in the acting chambers C, D is disabled from flowing into the acting subchamber E, and an expansion spring constant of the rubber elastic material wall 1 is substantially increased to generate a small device spring constant and a large device damping coefficient in a high frequency side.