PURPOSE: To enable caster angle and caster trail to be varied in a desired mode.

CONSTITUTION: In a suspension having a career 10, an upper arm 16, and a lower arm 18, are provided an upper link 36 and a lower link 38 which are connected to the upper and lower arms at their respective one-side ends, a pivot link 44 which is separated in the longitudinal direction from the upper and lower arms is supported on a chassis pivotably around a horizontal axial line 46, is connected at the upper end pivotally to the other end of the upper link and at the lower end pivotally to the other end of the lower link; and an actuator 50 which pivots the pivot link 44 around the axial line for positioning.