PURPOSE: To keep always suspension alignment constant and allow the change in toe angle of a front suspension to come near zero as much as possible by connecting a tie rod outer end with a knuckle arm through a hydraulic cylinder and expansively controlling the hydraulic cylinder in such a direction as the roll amount of a car body may be eliminated.

CONSTITUTION: A cylinder outer case 10 is arranged on the tie rod outer end connection portion of a knuckle arm 2, and a piston 12 integral with a stud where a tie rod 4 and a knuckle arm 2 are connected with each other is fitted to a cylinder outer casing 10 so that it can slide freely. Pressurized oil is fed or discharged from a port 16 or 17 in an upper or lower chamber A or B through a feed/discharge controller to control the expansion amount by the piston sliding motion of a hydraulic cylinder in the direction of eliminating this according to the amount of car body roll change or its prediction amount. This permits the outer end of the tie rod to keep always the height relationship of the connection portions in a lower arm constant, thus keeping a toe angle constant.