FLOW RATE CHARACTERISTIC FUNCTION IDENTIFICATION METHOD, FLOW RATE CHARACTERISTIC FUNCTION IDENTIFICATION DEVICE, STORAGE MEDIUM STORING FLOW RATE CHARACTERISTIC FUNCTION IDENTIFICATION PROGRAM, AND FLOW RATE SENSOR OR FLOW RATE CONTROL DEVICE USING THEM

To provide a flow rate characteristic function identification method, flow rate sensor, and flow rate characteristic function identification program that can set a flow rate characteristic function reflecting not only the type or shape of a fluid resistance but also the effects of states such as an attachment state of the fluid resistance, and calculate a flow rate with higher accuracy. An actual flow rate characteristic function, which is a flow rate characteristic function when an actual fluid resistance is provided in a flow path, is identified on the basis of multiple flow rate characteristic functions including a first reference flow rate characteristic function and a second reference flow rate characteristic function, and predetermined weighting.