In a damping force control system for switching over a shock absorber in the suspension of a vehicle from a low damping force operation to a high damping force operation when a vehicle height difference exceeds a determinate limit value, the shock abosrber is switched over from the low damping force operation to the high damping force operation after the lapse of a delay period so that the shock absorber is continually maintained at the high damping force operation from a time point at which the vehicle height difference generally reaches a peak amplitude of its variation for a time duration which is increased as a peak amplitude of the vehicle height difference exceeding the determinate limit value increases.