PURPOSE: To prevent hot-water from spouting from a shower head even when a bath occupant forgets to operate a change-over device, by automatically changing over to a second temperature control circuit side, which compares an output of a hot-water temperature setter with an output of a temperature sensor, by an output of a bath sensor when the occupant goes in or out of a bathtub.

CONSTITUTION: When an occupant goes in a bathtub B, a change-over switch 54 is changed over by an output of a pressure-change arithmetic circuit 1, and a hot-water set temperature of a second temperature control circuit 5b is given priority over that of a first temperature control circuit 5a by a bath sensor. This priority operation is effective within a time period set by a timer. Therefore, even in case a shower 27 in a bathroom is used within this time period, the hot-water is controlled at a hot-water set temperature set by a hot-water temperature setter 53 equipped on an auxiliary operating board C2. As a result, high temperature hot-water is prevented from spouting from the shower 27 even when the hot-water temperature is set for a high temperature by a main control board C1.