PURPOSE: To make the degree of shock absorption adjustable by installing at least two series of orifices having different diameters, and constituting it to rotate and control a disc so as to make one of the orifice series of the disc coincide with the ports of a body.

CONSTITUTION: In time of standing still, an electromagnet 22 remains unutilized, a spring 10 becomes extended, and a sleeve 18 hits on a stop abutting contact part. A disc 9 is in such an angular position as making an orifice 11 being large in diameter so as to be coincided with two ports 3 and 4, imparting a relatively soft suspension to wheels. Supposing that this suspension is intended to be temporarily hardened, a control grip is made to work so as to utilize the electromagnet 22. An iron core 24 is moved in the axial direction, and the sleeve 18 is driven till its slanting edge 24a is abutted to a surface 23a to which a supporting material 23 corresponds. During the process of this axial movement, a rod 15 will rotatively drive the disc 9 by the axial movement of a hole 17. After having rotated as far as an angle equal to a sector angle being distant from these two ranging orifices 11 and 12, the orifice 12, whose diameter is small, is opposed to both the ports 3 and 4 in a face-to-face manner.