A vehicle motion control system includes: a steering angle sensor for detecting a steering angle; a vehicle speed sensor for detecting a vehicle speed; a lateral acceleration sensor for detecting an actual lateral acceleration of a vehicle body; a reference lateral acceleration calculation unit configured to calculate a reference lateral acceleration from the steering angle and the vehicle speed; a required longitudinal force calculation unit configured to calculate a required longitudinal force for reducing a deviation of the actual lateral acceleration relative to the reference lateral acceleration; and a longitudinal force control unit configured to control an output of at least one of a brake and a power plant such that the required longitudinal force is generated.