PURPOSE: To maintain electric power consumption, especially an electric current value, sufficiently small and to almost perfectly prevent thermo-runaway of an electric current even at the time of using a device for a long period of time.

CONSTITUTION: A cooling means 13 of an electroviscous fluid 8 is provided in the periphery of a fluid surrounding space 7 where the fluid surrounding space 7 is provided, the electroviscous fluid 8 is sealed in the fluid surrounding space 7, a relative movement passage 9 of the electroviscous fluid 8 is partitioned in the fluid surrounding space 7 and electrodes 3, 4 are arranged in the relative movement passage 9.