<p>The present invention relates to water heating device including: a hot water tank having a body formed of an insulation wall, the body having an opening formed on the lower portion thereof, and a head detachably mounted on the opening; a water storage tank disposed above the hot water tank for storing water therein; a hot water inlet pipe disposed to pass through the head in such a manner as to be connected to the water storage tank and having an outlet port from which water is discharged located inside the hot water tank; a hot water outlet pipe having an inlet port shorter than the outlet port of the hot water inlet pipe and disposed to pass through the head in such a manner as to discharge the water in the hot water tank to the outside, the hot water outlet pipe having a hot water discharging valve mounted at the end thereof; and a heater mounted on the head for heating the water in the hot water tank.</p>
