To resolve the problem that, regarding a hot water supply device with a bathtab water reheating function and a heating function, when the device is not operated for a long period during an winter season, a valve and piping are frozen and cannot be used even though a heater is incorporated in the vicinity of a water supply and hot water supply connection port of a hot water supply apparatus for heating, and a gas plug is stopped, an operation switch has to be turned off, and a hot water supply plug has to be turned on to continue water to flaw from the preceding day when sever cold is predicted the following.

When an inflow thermistor 3 is reduced to temperature lower than a given temperature, a control means 34 communicating with water quantity sensor 2, a water flow rate control valve 32, and previously opened hot water supply cock 1 is provided. When freezing is predicted and no operation is effected for a long period, the control means 34 performs control in a manner that a freezing preventing switch is turned ON to keep the hot water supply cock 1 open so that water is made to flow to water supply and hot water supply circuit for prevention of freezing.