To provide a control device for a semiactive suspension system provided with a shock absorber which independently controls each of damping force characteristics of compression and extension strokes using an MR fluid.

This control device for semiactive suspension system comprises the shock absorber using at least one MR fluid. The shock absorber is provided with an extension valve and a compression valve capable of independently controlling each of the damping force characteristics in the compression and extension strokes. This device comprises: a normal running control unit for determining a ride value and a vertical speed of a filtering vehicle body based on a vehicle body vertical acceleration; an antiroll control unit for determining a roll value based on a vehicle speed and a steering angel; and a damping force adjusting unit for controlling the compression valve and the extension valve of the shock absorber based on the roll value and ride value under a predetermined condition and the vertical speed of the filtering vehicle body.