A supporting device for a packaged water dispenser that is capable of supporting a water bag of packaged water includes a supporting base and a supporting tray. The bottom of the supporting base is provided with a through hole for allowing an inlet conduit protruding from the top of the water dispenser to penetrate therein. The periphery of the supporting base is provided with a plurality of positioning pillars. Each positioning pillar is provided with an elastic element. The supporting tray is accommodated in the supporting base. The bottom of the supporting tray is formed into a funnel and provided with a penetrating hole to correspond to the position of the through hole. The penetrating hole allows the inlet conduit to penetrate therein. The periphery of the supporting tray is provided with a plurality of accommodating troughs for accommodating each positioning pillar and elastic element, so that the elastic element can support the supporting tray. Via this arrangement, the supporting tray raises the water bag of packaged water, so that the drinking water within the water bag can be concentrated and enter the water dispenser, thereby utilizing the water resource well.