Slip suppression control system for vehicle

A slip suppression control system for a vehicle comprises a monitored value detecting device (45) for detecting a monitored value corresponding to a difference between a rotational speed of a front wheel of the vehicle and a rotational speed of a rear wheel of the vehicle; a threshold determiner unit (46) configured to determine a relationship between the monitored value detected by the monitored value detecting device and plural thresholds; and a controller (47) configured to execute traction control for reducing a driving power of a drive wheel based on determination of the threshold determiner unit; wherein the plural thresholds have at least first and second thresholds, and the second threshold is set larger than the first threshold; and wherein the traction control includes an amount-change-based control such that a parameter corresponding to the driving power in a state where the traction control is being executed is made smaller in a case where the monitored value is larger than the second threshold than in a case where the monitored value is larger than the first threshold and smaller than the second threshold.