A duct-type air conditioning system comprising: an air conditioner; a plurality of dampers (9-1, 9-2, 9-3, 9-n) respectively provided in a plurality of ducts (7-1, 7-2, 7-3, 7-n) provided corresponding to a plurality air-conditioned spaces (10-1, 10-2, 10-3, 10-n), to which conditioned air from the air conditioner is to be supplied, to bring an air trunk in each of the ducts (7-1, 7-2, 7-3, 7-n) into an opened state or closed state individually; a plurality of outlets (8-1, 8-2, 8-3, 8-n) respectively provided at ends of the ducts (7-1, 7-2, 7-3, 7-n); and a control device that is configured to control the air conditioner and the dampers (9-1, 9-2, 9-3, 9-n), characterized in that the control device includes a controlled air-volume calculation unit (400, 410, 420) that, when the air conditioner is to perform automatic air volume adjustment, is configured to calculate a controlled air volume of an indoor unit constituting the air conditioner, on the basis of: an opening ratio, which is a ratio of sum of numbers or areas of opened outlets (8-1, 8-2, 8-3, 8-n) provided in the duct (7-1, 7-2, 7-3, 7-n) having the damper (9-1, 9-2, 9-3, 9-n) in an opened state with respect to sum of numbers or areas of the outlets (8-1, 8-2, 8-3, 8-n) respectively provided in the air-conditioned spaces (10-1, 10-2, 10-3, 10-n); and a temperature difference between a target temperature of an air-conditioned space (10-1, 10-2, 10-3, 10-n) and a temperature measured in the air-conditioned space (10-1, 10-2, 10-3, 10-n) where at least one of the opened outlets (8-1, 8-2, 8-3, 8-n) is present. an air conditioner; a plurality of dampers (9-1, 9-2, 9-3, 9-n) respectively provided in a plurality of ducts (7-1, 7-2, 7-3, 7-n) provided corresponding to a plurality air-conditioned spaces (10-1, 10-2, 10-3, 10-n), to which conditioned air from the air conditioner is to be supplied, to bring an air trunk in each of the ducts (7-1, 7-2, 7-3, 7-n) into an opened state or closed state individually; a plurality of outlets (8-1, 8-2, 8-3, 8-n) respectively provided at ends of the ducts (7-1, 7-2, 7-3, 7-n); and a control device that is configured to control the air conditioner and the dampers (9-1, 9-2, 9-3, 9-n), characterized in that the control device includes a controlled air-volume calculation unit (400, 410, 420) that, when the air conditioner is to perform automatic air volume adjustment, is configured to calculate a controlled air volume of an indoor unit constituting the air conditioner, on the basis of: an opening ratio, which is a ratio of sum of numbers or areas of opened outlets (8-1, 8-2, 8-3, 8-n) provided in the duct (7-1, 7-2, 7-3, 7-n) having the damper (9-1, 9-2, 9-3, 9-n) in an opened state with respect to sum of numbers or areas of the outlets (8-1, 8-2, 8-3, 8-n) respectively provided in the air-conditioned spaces (10-1, 10-2, 10-3, 10-n); and a temperature difference between a target temperature of an air-conditioned space (10-1, 10-2, 10-3, 10-n) and a temperature measured in the air-conditioned space (10-1, 10-2, 10-3, 10-n) where at least one of the opened outlets (8-1, 8-2, 8-3, 8-n) is present. an opening ratio, which is a ratio of sum of numbers or areas of opened outlets (8-1, 8-2, 8-3, 8-n) provided in the duct (7-1, 7-2, 7-3, 7-n) having the damper (9-1, 9-2, 9-3, 9-n) in an opened state with respect to sum of numbers or areas of the outlets (8-1, 8-2, 8-3, 8-n) respectively provided in the air-conditioned spaces (10-1, 10-2, 10-3, 10-n); and a temperature difference between a target temperature of an air-conditioned space (10-1, 10-2, 10-3, 10-n) and a temperature measured in the air-conditioned space (10-1, 10-2, 10-3, 10-n) where at least one of the opened outlets (8-1, 8-2, 8-3, 8-n) is present.