PURPOSE: To eliminate a moment when the viscousity of an electric viscous fouid is excessively lowered even if an electric field which changes periodically is applied to an electroviscous fluid.

CONSTITUTION: An orifice 13 where an electroviscous fluid passes is formed by a cylindrical upper outside electrode 4A, an upper inside electrode 4B, a cylindrical lower outside electrode 5A, and a lower inside electrode 5B in an inner cylinder of a shock absorber 1. The electrodes 4A, 4B and the electrodes 5A, 5B are made electrically independent by ring-shaped insulators 6, 7, and the electrodes 4A, 4B, 5A, 5B can be individually supplied with control voltage by a controller 20. A phase conversion circuit 20c is provided in the controller 20, whereby an A.C. voltage phase-shifted by 90° can be supplied between the electrodes 4A and 4B, and between the electrodes 5A and 5B.