In order to restrain generation of a peak in the measured flow rate, a fluid control unit measures a flow rate of a fluid in a channel and outputs a signal indicating a valve operation amount of a fluid control valve obtained based on a deviation between a preset flow rate and a measured flow rate and a control coefficient, and the control coefficient for a stable state and the control coefficient for a transitional state are so set to moderate fluctuation of the valve operation amount to the deviation more in the transitional state than in the stable state. At or shortly after a timing when the stable state is switched to the transitional state, a signal is output that indicates an operation amount for a switching time calculated based on each of the operation amounts output at a plurality of timings in the stable state.