An attaching system of an exhaust gas recirculation valve includes: an attachment unit 2 to be communicated with an exhaust gas circulation passage of an internal combustion engine; and an exhaust gas recirculation valve 1 that is fitted to the attachment unit and that has an exhaust gas passage to be communicated with the exhaust gas circulation passage, wherein the exhaust gas recirculation valve has a water-cooled passage 12 to be communicated with a water-cooled passage 15 for cooling the exhaust gas passage provided with the attachment unit, when fitted to the attachment unit.