A driving force control system for vehicle for controlling a target speed of an engine serving as a prime mover by selecting a control mode based on an index representing a driving preference of a driver. The control mode is selected from a first mode for operating the engine to achieve the target speed while optimizing a fuel economy, and a second mode for operating the engine to achieve the target speed at a speed lower than that achieved while optimizing the fuel economy. The driving force control system is configured to determine a lower limit speed of the engine based on the index provided that the second mode is selected, and to restrict a lower limit value of the target speed of the engine to the lower limit speed in case the target speed of the engine exceeds the lower limit speed under the second mode.