To permit a warm holding time zone to be automatically delayed in a condition suited for the actual use to reduce the running cost for the warm hold control.

In the hot water supply in which a hot warm control means H for heating water from a water inlet line 5 by heating means 2, 3 and feeding it to a hot water outlet line 6 and the hot warm control means H is provided and constituted so as to execute a hot water feed control for actuating the heating means 2, 3 to start and stop the hot water feed and warm holding control for starting a warm holding operation, when warm holding start setting conditions are met in a warm holding time zone set by time zone setting means 102 and stopping operating the warm holding operation when warm holding stop setting conditions are met, the time zone setting means 102 obtains executing information corresponding to a time initiating the hot water feed control to delay an execution start time feasible for the warm holding control, based on the executing information.