To sustain a comfortable temperature in a bath room by providing means for cooling a circulation channel with water from the outside thereof and exchanging heat between hot water in the circulation channel and cooling water on the outside thereof.

A water supply hose 3 and a drainage hose 4 are coupled with a circulation channel 10 having one end part coupled with a bypath 11 in front of a heating bath 8 and the other end part coupled with the bypath 11 on the downstream side of a sterilization tank 9. A cooling tank 12 is disposed as means generating heat-exchange action for warming the water by causing the cooling water to act on the circulation channel 10 on the upstream side of the joint of the bypath 11 and the circulation channel 10 on the downstream side of the sterilization tank 9 while enclosing the circulation channel 10 partially. According to the arrangement, a comfortable temperature can be sustained in the bath room by introducing the cooling water warmed through heat-exchange at a part of the circulation channel 10 into the bath room.