Abstract: Provided is a device of evaluating a semiconductor manufacturing apparatus in which flow rate control units are installed in flow paths through which gas supplied from gas supply sources flows, and an operation of each flow rate control unit is controlled according to time-serially defined process conditions to adjust a supply operation of gas in a semiconductor manufacturing process. The device includes: a storage unit to store layouts of the flow rate control units; an obtaining unit configured to obtain information of the process conditions at an instant of time; a specifying unit configured to specify an operational state of each flow rate control unit based on the information of the process conditions; and a determination unit configured to determine an internal gas state of a flow path arranged over upstream and downstream sides of each flow rate control unit based on the specified operational state and the layouts.