1. A method for modifying a causative signal outputted from a control unit of a machine which is operable by the causative signal, based on an evaluation signal of operation of the machine, said control unit outputting the causative signal when receiving indicative signals indicating operation of the machine, said control unit comprising: (i) a base value output unit to output a base value of a causative signal when receiving indicative signals; (ii) an evaluation unit programmed to output an evaluation signal of operation of the machine when receiving pre-selected signals associated with operation of the machine; and (iii) an evolution unit comprising an evolution neural network programmed to output and add a compensation value to the base value of the causative signal when receiving indicative signals, said evolution neural network provided with a predetermined genetic algorithm using, as genes, coupling coefficients regulating the relationship between output and input of the evolution neural network to select coupling coefficients based upon an evaluation signal of operation of the machine; wherein the base value output unit and the evolution unit are placed in parallel to receive indicative signals and output causative signals to be combined, said method comprising the steps of: (a) activating the base value output unit to output a base value of the causative signal; (b) activating the evolution neural network of the evolution unit to output and add a compensation value to the base value of the causative signal to operate the machine; (c) activating the evaluation unit to output an evaluation signal of operation of the machine and input the evaluation signal into the evolution unit; and (d) selecting coupling coefficients by the predetermined genetic algorithm using coupling coefficients as genes based upon the evaluation signal, while the machine is operated, thereby outputting and adding a compensation value to the base value of the causative signal to operate the machine by using the evolution unit with the selected coupling coefficients.