The present disclosure discloses a defrosting device, including a heating unit provided in an evaporator; and a heat pipe, both end portions of which are connected to an inlet and an outlet of the heating unit, respectively, and at least part of which is disposed adjacent to a cooling tube to dissipate heat to the cooling tube of the evaporator due to high-temperature working fluid heated and transferred by the heating unit, wherein the heating unit includes a heater case provided with a vacant space therein, and provided with the inlet and the outlet at positions separated from each other, respectively, along a length direction; and a heater attached to an outer surface of the heater case to heat working fluid within the heater case.