To prevent contact of metal members on a vehicle body side and on a piston rod side around the opening of a vehicle body side member without deteriorating the durability of a cushion rubber in a vibration isolator to elastically joint the piston rod of a shock absorber for a vehicle body in a suspension mechanism of a vehicle.

The vibration isolator 10 comprises: the vehicle body side member 12 having the opening 13; an upper side mounting member 14 and a lower side mounting member 16 arranged upwards or downwards; and the upper side cushion rubber 18 and the lower side cushion rubber 20 disposed between the mounting member and the vehicle body side member. A cylindrical rubber 28 which protrudes toward an axial direction A, and surrounds the outer periphery of the piston rod 1 in the opening 13 of the vehicle body side member 12, is integrally installed in the lower surface 18c of the upper cushion rubber 18. An annular recess 30 dropped in the axial direction is installed in the root 28a outer periphery of the cylindrical rubber 28.