PURPOSE: To promote the reliability of ventilation control in a road tunnel by calculating standard airflow of ventilators based on traffic forecasts in a ventilation operation plan so that concentration of pollution is less than upper limited value set in advance, and correcting the airflow of ventilators.

CONSTITUTION: Cars passing through a road tunnel 1 are detected by a traffic detector 7, and concentration of pollution in the tunnel 1 is detected by a plurality of VI meters 8-11. After that, forecasts are made with a traffic forecast section 13 based on data detected by the traffic detector 7, and as a result, standard airflow of the first dust collector 2, second dust collector 3, exhauster 5 and blower 6 is calculated by a ventilation operation planning section 14 so that VI value is in excess of VI value set in advance. The result obtained through a feed-back control operation section 15 is distributed and processed through a ventilator load distribution and processing section 16 based on the standard airflow so that pollution detected value detected by the VI meters 8-11 is approached to a target value.