The present disclosure discloses a defrosting device, including a heating unit provided at a lower side of an evaporator, and configured to heat working fluid therein; and a plurality of heat pipes, both end portions of which are connected to an inlet and an outlet of the heating unit, respectively, and at least part of which are disposed adjacent to a cooling tube of the evaporator to emit heat to the cooling tube due to high temperature working fluid heated and transferred by the heating unit, wherein the plurality of heat pipes are configured with a first heat pipe and a second heat pipe disposed to form two rows on a front portion and a rear portion of the evaporator, respectively, and the first heat pipe and the second heat pipe are formed in different lengths.