PURPOSE: To raise the isolating function against fine vibration by a method in which anchor pins projected from upper and lower flanges are inserted into the holes of an outer shim set on upper and lower ends of a lead plug, and a laminated rubber layer is set between the flanges and the outer shim.

CONSTITUTION: A laminated rubber 2 consisting of steel plates and rubber is set around a lead plug 1, and anchor pins 3a projected from upper and lower flanges 3 are inserted into the holes 4a of outer shims 4 set on upper and lower ends of the plug 1. A laminated rubber layer 5 consisting of steel plates and rubber is set between the flanges 3 and the shims 4. Since the development of high early-period rigidity of the plug 1 can be suppressed by the rubber layer 5, isolating function against fine vibration in the vertical and horizontal directions can be raised.