An indoor unit for an air conditioner, the indoor unit comprising: an indoor fan for sucking air in an axial direction thereof and radially blowing out the air; a heat exchange part, connected in a refrigerant circuit and disposed to surround the indoor fan, for exchanging heat between the air blown out of the indoor fan and refrigerant in the refrigerant circuit; and a casing containing the indoor fan and the heat exchange part and having an air supply part formed therein to supply air to a room in different directions, wherein the refrigerant circuit is operable in a refrigeration cycle in which the high-side pressure is equal to or above the critical pressure of the refrigerant, the indoor unit is capable of performing a heating operation in which the heat exchange part serves as a gas cooler in the refrigerant circuit, the heat exchange part includes one or more heat exchangers; each heat exchanger comprises one end and another end; wherein each of the one or more heat exchangers respectively has a plurality of refrigerant flow paths connected in parallel with each other in the refrigerant circuit to extend in a direction of the perimeter of the heat exchange part and arranged alongside each other in the axial direction of the indoor fan, the plurality of the refrigerant flow paths includes a plurality of first flow paths and second flow paths, the first flow paths have their ports (49a, 49b) at the one end of the heat exchanger, the second flow paths have their ports (49a, 49b) at the other end of the heat exchanger, the ports (49a, 49b) of the first flow paths are connected to a pair of a header and a flow divider at the one end of the heat exchanger; the ports (49a, 49b) of the second flow paths are connected to another pair of a header and a flow divider at the other end of the heat exchanger; and during the heating operation, the direction of refrigerant flowing into the first flow paths is opposite to the direction of refrigerant flowing into the second flow paths with reference to the direction of the perimeter of the heat exchange part. an indoor fan for sucking air in an axial direction thereof and radially blowing out the air; a heat exchange part, connected in a refrigerant circuit and disposed to surround the indoor fan, for exchanging heat between the air blown out of the indoor fan and refrigerant in the refrigerant circuit; and a casing containing the indoor fan and the heat exchange part and having an air supply part formed therein to supply air to a room in different directions, wherein the refrigerant circuit is operable in a refrigeration cycle in which the high-side pressure is equal to or above the critical pressure of the refrigerant, the indoor unit is capable of performing a heating operation in which the heat exchange part serves as a gas cooler in the refrigerant circuit, the heat exchange part includes one or more heat exchangers; each heat exchanger comprises one end and another end; wherein each of the one or more heat exchangers respectively has a plurality of refrigerant flow paths connected in parallel with each other in the refrigerant circuit to extend in a direction of the perimeter of the heat exchange part and arranged alongside each other in the axial direction of the indoor fan, the plurality of the refrigerant flow paths includes a plurality of first flow paths and second flow paths, the first flow paths have their ports (49a, 49b) at the one end of the heat exchanger, the second flow paths have their ports (49a, 49b) at the other end of the heat exchanger, the ports (49a, 49b) of the first flow paths are connected to a pair of a header and a flow divider at the one end of the heat exchanger; the ports (49a, 49b) of the second flow paths are connected to another pair of a header and a flow divider at the other end of the heat exchanger; and during the heating operation, the direction of refrigerant flowing into the first flow paths is opposite to the direction of refrigerant flowing into the second flow paths with reference to the direction of the perimeter of the heat exchange part.