The present invention provides a processing system, a processing method and a program, which can readily control a gas flow rate. A vertical-type heating apparatus 1 includes a plurality of gas supply pipes 16 to 20 each adapted for supplying a processing gas into a reaction vessel 2 configured to contain therein semiconductor wafers W. For the gas supply pipes 16 to 20, flow rate control units 21 to 25 are provided, respectively, for controlling each flow rate. In a control unit 50, processing conditions including the flow rate of the processing gas and a film thickness-flow rate-relationship model indicative of a relationship between the flow rate of the processing gas and a film thickness, are stored. The control unit 50 calculates the flow rate of the processing gas based on a process result obtained by processing the semiconductor wafers W under the processing conditions as well as on the film thickness-flow rate-relationship model, so as to process the semiconductor wafers W, while controlling the respective flow rate control units 21 to 25, such that the flow rate of the processing gas will be changed into the calculated flow rate of the processing gas.