The behavior of combined vehicles is easily affected by the uncertainties of vehicle parameters. It is very difficult for the drivers to achieve good handling stability. However, if the behavior of actual combined vehicles tracks the designed ideal vehicle, the good handling property can be maintained for the large uncertain variation in the dynamics of actual combined vehicles. Based on this notion, the adaptive steering controller is proposed to achieve good handling property even for large uncertain variation of vehicle dynamics. Moreover, in the control system of this paper, the dynamics of steering system such as steer-by-wire system is considered. The proposed adaptive steering controllers have good robust performance for the uncertainties of combined vehicles with the steering system. The robust performance can be easily improved by setting two design parameters.