A flow rate control valve includes a second substrate having a flexible thin film and interposed between a first substrate having a heating mechanism and a third substrate having a sealing section. The first substrate and the second substrate close an internal space formed adjacent to the heating mechanism and filled with an expandable material. The sealing section and the flexible thin film function together as a valve. The heating mechanism heats and expands the expandable material whose pressure is detected by pressure-detecting sensors. The detected pressure value is fed back to a control mechanism of the heating mechanism for opening/closing a fluid flow passage and controlling the valve opening degree.