PURPOSE: To improve the vehicular comfortable ride and steering stability by deciding the most suitable profit automatically, while changing the necessary common ground between a body acceleration, the stroke of a wheel and the power of a controller.

CONSTITUTION: This closed loop control system suitable for an active suspension system has a controller 351 for outputting a control signal to a physical system 350, which issues the control signal by adding control profits Ka, Kp generated by the action of modules 352-357. The control profits Ka, Kp are changed so as to be suitable for the common ground between a body acceleration, the stroke of a wheel and the power of the controller 351. An input signal is received by the filter 357 with a weight and here, the weighted average value of the frequency of a time variable input signal for a sensitive filter 355 is found out and the output is weighted by plural weighting coefficient in a block 356 and outputted.