It is aimed at in the present study to maintain a desired alveolar CO2 concentration by giving appropriate ventilation. It is, however, difficult to synthesize an adequate control system of respiration, because of a complicated respiratory regulation system which is dependent on its chronic change and difference of individuals. Hereby, effect of metabolic rate change is regarded as a characteristic change of dynamics resulting from parameter change of the respiratory regulation system whose input and output are ventilation and alveolar CO2 concentration, respectively. Based on the theoretical investigation of a simulation experiment, artificial respiration using fuzzy logic is proposed to maintain an alveolar CO2 concentration within an appropriate range of value. It is confirmed with its satisfactory stability and controlling performance by physiological experiments on healthy subjects.