A driving force control system for use in a vehicle, the vehicle including an engine, a driving wheel to be driven by motive power from the engine, and a centrifugal clutch provided in a transmission path of motive power between the engine and the driving wheel, the driving force control system being configured to adjust slipping of the driving wheel in a state in which the driving wheel is slipping, wherein, the centrifugal clutch includes an upstream member mechanically connected to the engine to rotate, and a downstream member to be mechanically connected with or disengaged from the upstream member based on a centrifugal force occurring in accordance with rotation of the upstream member, wherein, with a centrifugal force which is in accordance with rotation of the upstream member, automatically turns ON or OFF transmission of motive power between an upstream-of-centrifugal-clutch path from the engine to the upstream member and a downstream-of-centrifugal-clutch path from the downstream member to the driving wheel; and the driving force control system exerts control so that, in a state in which the driving wheel is slipping, a reduction rate under non-connection concerning the upstream-of-centrifugal-clutch path is smaller than a reduction rate under connection concerning the upstream-of-centrifugal-clutch path, wherein the reduction rate under non-connection concerning the upstream-of-centrifugal-clutch path is a reduction rate in rotation speed of the upstream-of-centrifugal-clutch path when a difference exists between a rotation speed of the upstream member of the centrifugal clutch and a rotation speed of the downstream member of the centrifugal clutch and the reduction rate under connection concerning the upstream-of-centrifugal-clutch path is a reduction rate in rotation speed of the upstream-of-centrifugal-clutch path when a rotation speed of the upstream member of the centrifugal clutch is equal to a rotation speed of the downstream member of the centrifugal clutch before a difference emerges between a rotation speed of the upstream member of the centrifugal clutch and a rotation speed of the downstream member of the centrifugal clutch, characterized in that the driving force control system includes a control section to perform traction control in a state in which the driving wheel is slipping, wherein the driving force control system further comprises a first sensor to detect a rotation speed of the upstream-of-centrifugal-clutch path, and a second sensor to detect a rotation speed of the downstream-of-centrifugal-clutch path; and the control section suspends the traction control or loosens the traction control when the rotation speed of the upstream-of-centrifugal-clutch path detected by the first sensor is less than, or equal to or smaller than, a preset first threshold (a) and the rotation speed of the downstream-of-centrifugal-clutch path detected by the second sensor is less than, or equal to or smaller than, a preset second threshold (β). an engine, a driving wheel to be driven by motive power from the engine, and a centrifugal clutch provided in a transmission path of motive power between the engine and the driving wheel, an upstream member mechanically connected to the engine to rotate, and a downstream member to be mechanically connected with or disengaged from the upstream member based on a centrifugal force occurring in accordance with rotation of the upstream member, wherein, the reduction rate under non-connection concerning the upstream-of-centrifugal-clutch path is a reduction rate in rotation speed of the upstream-of-centrifugal-clutch path when a difference exists between a rotation speed of the upstream member of the centrifugal clutch and a rotation speed of the downstream member of the centrifugal clutch and the reduction rate under connection concerning the upstream-of-centrifugal-clutch path is a reduction rate in rotation speed of the upstream-of-centrifugal-clutch path when a rotation speed of the upstream member of the centrifugal clutch is equal to a rotation speed of the downstream member of the centrifugal clutch before a difference emerges between a rotation speed of the upstream member of the centrifugal clutch and a rotation speed of the downstream member of the centrifugal clutch, characterized in that the driving force control system includes a control section to perform traction control in a state in which the driving wheel is slipping, wherein the driving force control system further comprises a first sensor to detect a rotation speed of the upstream-of-centrifugal-clutch path, and a second sensor to detect a rotation speed of the downstream-of-centrifugal-clutch path; and the control section suspends the traction control or loosens the traction control when the rotation speed of the upstream-of-centrifugal-clutch path detected by the first sensor is less than, or equal to or smaller than, a preset first threshold (a) and the rotation speed of the downstream-of-centrifugal-clutch path detected by the second sensor is less than, or equal to or smaller than, a preset second threshold (β).