A water discharge valve device includes: a water discharge valve unit which has a valve element for opening and closing a discharge port and a control casing for controlling an up-down movement of the valve element; a casing module which includes a peripheral wall extending upwardly from a bottom wall of a water storage tank while surrounding peripheries of the discharge port and the control casing of the water discharge valve unit, to define an upwardly open space therebetween, an opening formed to penetrate through the peripheral wall, and a switching valve attached to the peripheral wall and adapted to open and close the opening; and a communication port formed in a peripheral plane extending from the control casing of the water discharge valve unit to the discharge port, to provide fluid communication between the casing module and the discharge port.