This air conditioning and ventilation system is provided with the following: one or more ventilation devices (3) that circulate air between a plurality of rooms; one or more air conditioning devices (2) provided in at least one of the plurality of rooms; a motion detector (104) provided in each of the plurality of rooms for detecting the presence of a person in the rooms; an air conditioning and ventilation optimal operation predictor (112) that predicts, for each of the plurality of rooms, the presence or absence of a person in a room or the human presence rate, which is the number of people present in a room per unit period of time, on the basis of past detection results detected by the motion detector (104); and a controller (5) that controls the ventilation devices (3) and the air conditioning devices (2) on the basis of the prediction results from the air conditioning and ventilation optimal operation predictor (112).
