A flow rate control device capable of suppressing overshoot while improving responsiveness at the beginning of flow rate control includes: a flow rate meter that measures a flow rate of a fluid flowing through a flow path; a flow rate regulating valve that regulates the flow rate of the fluid flowing through the flow path; and a control part that controls an opening degree of the flow rate regulating valve based on a measurement result of the flow rate meter, the flow rate control device has: a low flow rate rapid valve opening function that accelerates an outflow of the fluid by forcibly opening the opening degree of the flow rate regulating valve from fully closed degree to a designated opening degree when the opening degree of the flow regulating valve is fully closed and a flow rate control is started; and an overshoot suppressing function that is used for suppressing the overshoot by making the flow rate control stand by until a preset standby time or a preset flow rate threshold is reached immediately after the low flow rate rapid valve opening function works.