PURPOSE: To control airflow direction so as not to hit human bodies especially upon room heating operation or the like, by a method wherein the position of the human bodies and the distribution of the group of men are judged by detecting infrared rays, emitted from the human body, and the direction of airflow is controlled from information on the infrared rays.

CONSTITUTION: The title system consists of a detecting unit 1, equipped with detecting means 1a, 1b, 1c detecting the infrared rays of a human body and provided with three directivities, amplifying means 2a, 2b, 2c, amplifying these detecting signals, a comparing means 4, comparing a signal constituted by a reference value comparing means 6 with a predetermined value through integrating filters 5a, 5b, 5c obtianing the time average of the amplified signals, a judging means 8, judging the position of the human body from the output of the comparing means 4 and outputting driving signals to airflow direction control blades 11a, 11b, and airflow direction control blade driving means 9a, 9b, driving the airflow direction control blades 11a, 11b by the driving signals while the airflow direction control blades are driven into the direction, in which the human body is not detected by the output of the comparing means 4. Accordingly, the position of the human body and the distribution of the group of men may be judged by detecting infrared rays emitted from the human body and the direction of airflow may be controlled from the information on the infrared rays.