A suspension is provided which can not only generate a damping force between sprung mass and unsprung mass but also steer a wheel. A suspension includes: a shaft coupled to sprung mass of a vehicle, the shaft having a screw groove and a spline groove formed thereon; a ball screw nut assembled to the shaft via a ball; a ball spline nut assembled to the shaft via a ball; a ball screw-specific motor connected to the ball screw nut; a ball spline-specific motor connected to the ball spline nut; and a case coupled to unsprung mass of the vehicle, the case being configured to hold the ball screw-specific motor and the ball spline-specific motor. The ball spline-specific motor rotates the ball spline nut and the shaft relative to the case.