A damping force control apparatus for a suspension that is applied to a damper whose damping force is capable of being set based on a damping force control value and that controls the damping force control value, the damper being attached to a support portion with a buffer member interposed between the support portion of a vehicle body and a cylinder of the damper, the apparatus comprising: a displacement related quantity estimation device which estimates relative displacement (r) of a vehicle wheel with respect to the vehicle body and a relative speed (y) of the vehicle wheel with respect to the vehicle body as estimated relative displacement and an estimated relative speed; and a damping force control value calculation device which determines the damping force control value so as to suppress vibration of the vehicle body based on state variables provided from the vehicle body and the estimated relative speed which is estimated by the displacement related quantity estimation device, characterized in that the displacement related quantity estimation device estimates the estimated relative speed and the estimated relative displacement based on the state variables, the damping force control value which is determined by the damping force control calculation device, and the estimated relative speed and the estimated relative displacement which are estimated by the displacement related quantity estimation device itself, wherein the displacement related quantity estimation device includes a nonlinear component calculation section which derives a nonlinear component (fnob), to which the buffer member contributes, with respect to the estimated relative displacement based on the damping force control value determined by the damping force control value calculation device and the estimated relative displacement estimated by the displacement related quantity estimation device, and a displacement related quantity calculation section which estimates the estimated relative speed and the estimated relative displacement based on the nonlinear component and the state variables. a displacement related quantity estimation device which estimates relative displacement (r) of a vehicle wheel with respect to the vehicle body and a relative speed (y) of the vehicle wheel with respect to the vehicle body as estimated relative displacement and an estimated relative speed; and a damping force control value calculation device which determines the damping force control value so as to suppress vibration of the vehicle body based on state variables provided from the vehicle body and the estimated relative speed which is estimated by the displacement related quantity estimation device, characterized in that the displacement related quantity estimation device estimates the estimated relative speed and the estimated relative displacement based on the state variables, the damping force control value which is determined by the damping force control calculation device, and the estimated relative speed and the estimated relative displacement which are estimated by the displacement related quantity estimation device itself, wherein the displacement related quantity estimation device includes a nonlinear component calculation section which derives a nonlinear component (fnob), to which the buffer member contributes, with respect to the estimated relative displacement based on the damping force control value determined by the damping force control value calculation device and the estimated relative displacement estimated by the displacement related quantity estimation device, and a displacement related quantity calculation section which estimates the estimated relative speed and the estimated relative displacement based on the nonlinear component and the state variables. a nonlinear component calculation section which derives a nonlinear component (fnob), to which the buffer member contributes, with respect to the estimated relative displacement based on the damping force control value determined by the damping force control value calculation device and the estimated relative displacement estimated by the displacement related quantity estimation device, and a displacement related quantity calculation section which estimates the estimated relative speed and the estimated relative displacement based on the nonlinear component and the state variables.