A PID controller system comprises a PID controller for PID controlling a process standing for an object to be controlled, and an automatic adjuster being responsive to a variable relating to the manipulation of the PID controller and the response shape of the control variable from the process to obtain necessary performance indexes and preparing, on the basis of the performance indexes, optimum control parameters for tuning the actual control variable to the control command value, the optimum control parameters being fedback from the automatic adjuster to the PID controller.