A hot-water supply device (1) includes a heat exchanger (4) that performs heat exchange, a hot-water supply tank (3), a delivery piping that delivers hot water from the hot-water supply tank (3) to the heat exchanger (4), a return piping that feeds the hot water from the heat exchanger (4) to the hot-water supply tank (3), and a scale adhering material (10). The scale adhering material (10) is disposed in a channel of the hot water including the hot-water supply tank (3), the delivery piping, the heat exchanger (4), and/or the return piping. When an area of an aperture (13) of the scale adhering material (10) is S, and an outer circumference is P, a representative length L of the aperture (13) defined as L = 4S/P is equal to or greater than 1.0 mm and equal to or smaller than 20 mm.