To conduct the determination of the transition of the state of the fluid distribution of contaminants in a tunnel and the evaluation of a ventilation effect easily when a roadway is ventilated.

The tunnel ventilation monitor has an arithmetic processing unit 3 constituted of a computer acquiring and arithmetically processing various measurement information related to tunnel ventilation such as the measurement information of the traffic volume of a roadway tunnel to be ventilated, the measurement information of the concentration of contaminants based on the exhaust gas of a travelling car, and a monitor display 4 screen-displaying the monitor display output of the arithmetic processing unit 3. The data of the state of the fluid distribution of the contaminants in the roadway tunnel are computed by arithmetic processing, graph display outputs under the state of the fluid distribution of the contaminants using either one of an axis of abscissa or an axis of ordinate as the tunnel roadway direction and the other of both axes as the concentration of the contaminants are formed repeatedly as monitor display outputs on the basis of the data, and the state of the fluid distribution of the contaminants in the roadway tunnel is indicated graphically on the monitor display 4 by dynamic picture planes by the monitor display outputs.