Apparatus and method for controlling heating operation in heat pump system

There is provided an air conditioner, and more particularly, an apparatus and method for controlling a heating operation in a heat pump system, in which a continuous heating operation is provided. 1. The apparatus for controlling a heating operation in a heat pump system includes: at least one compressor for compressing a refrigerant into a high-temperature and high-pressure refrigerant vapor; a passage switching unit for switching a refrigerant circulation passage depending on a heating mode or a cooling mode; an indoor heat exchanger for condensing the high-temperature and high-pressure refrigerant vapor for a heating operation or a defrosting/heating operation of the heating mode; an expansion unit through which the condensed refrigerant passes during the defrosting/heating operation; an outdoor heat exchanger for defrosting at least one tube region by using the condensed refrigerant discharged from the expansion unit; and a defrosting control unit for expanding and decompressing the refrigerant that flows between the tube regions, or for bypassing the refrigerant.