To provide a bathtub water reusing device which is not a hindrance during bathing and cleaning, dispenses with preparation and a cleanup for using bathtub water as water for a washing machine, can prevent mold from being gathered by preventing leakage of moisture outside a bathroom, and enables the water remaining in piping from the bathtub to the washing machine to be discharged to a side of the bathtub by an ejector action when the bathtub is filled with hot water and when a reheating operation is conducted.

In the bathtub water reusing device for using the bathtub water as the water for the washing machine, a branched part is provided midway along a circulating channel composed of the bathtub and a water heater with a reheating function, which is equipped with a reheating pump, a distributing water pipe for distributing the bathtub water to a side of the washing machine is provided outside the bathroom, and an ejector is provided inside the branched part.