A vehicle dynamics behavior reproduction system capable of describing accurately behavior of a motor vehicle in a lateral direction even for nonlinear driving situation includes a vertical wheel force arithmetic module (105), a lateral wheel force arithmetic module (110), a cornering stiffness adaptation module (115), a state space model/observer unit (120), a selector (130), a delay module (135), and a tire side slip angle arithmetic module (125). Vertical wheel forces (FZ.sub.ij) and tire side slip angles (.alpha..sub.ij) are determined by using sensor information and estimated values while lateral wheel forces (FY.sub.ij) are determined in accordance with a relatively simple nonlinear approximation equation. The lateral wheel force (FY.sub.ij) and the tire side slip angle (.alpha..sub.ij) provide bases for adaptation of cornering stiffnesses at individual wheels. Vehicle motion is accurately described to a marginal stability by using adapted cornering stiffnesses (C.sub.ij) and other information.