To provide a dial position deciding device for a flow control valve, a dial position deciding program for the flow control valve, and a storage medium, capable of simply and easily setting a flow rate while easily correcting the viscosity coefficient of fluid and differential pressure in the gateway of the flow control valve when setting the opening of the flow control valve for a target flow rate.

The dial position deciding scale for the flow control valve comprises a basal plate 1 marked with circular scales 3, 4, and a rotary disc 2. The rotary disc 2 is laid on the basal plate 1 whose scales 3, 4 are arranged on the outer periphery, and connected thereto rotatably at its center point 7. Values for a flow rate and values for pressure are marked on the basal plate as logarithms, and values for the rotating number of a knob for the flow control valve and values for the viscosity coefficient of fluid are marked on the rotary disc as logarithms. The flow rate of the fluid is determined while selecting the value for the fluid from the scales for the viscosity coefficient and rotating the disc so that the value corresponds to the scale for the pressure of the fluid. The value for the rotating number of the knob for the flow control valve on the rotary disc corresponding to the scale for the flow rate on the basal plate at this time can be directly read as the rotating position of the knob.