A setting value change device is provided whereby change operations to correct temperature setting values or hot water amount values by drag operations are easy. A controller causes a display to display a drag button and a movement path on which the drag button moves. Additionally, the controller provides, on a touch sensor, a drag area for detecting a drag input on the drag button and a reference point disposed at a location off the movement path. Moreover, the controller is configured to set the drag area larger than the display range of the movement path, move the drag button to a crossing point where a straight line or specific curve connecting the reference point to a drag operation position in the drag area crosses the movement path, and change the temperature setting value to the value corresponding to the position of the drag button.