A refrigerant cycle apparatus comprising: a refrigerant circuit including a compressor configured to compress a refrigerant, a first heat exchange unit having a main heat exchange unit, a sub heat exchange unit, and a pressure loss portion disposed on a flow path of the refrigerant between the main heat exchange unit and the sub heat exchange unit, a second heat exchange unit, an expansion mechanism disposed on the flow path of the refrigerant between the first heat exchange unit and the second heat exchange unit and configured to decompress the refrigerant, and a flow direction switching mechanism configured to switch a flow direction of the refrigerant discharged from the compressor, between a first flow direction of the refrigerant flowing in an order of the second heat exchange unit, the expansion mechanism, the sub heat exchange unit, the pressure loss portion, and the main heat exchange unit, and a second flow direction of the refrigerant flowing in a direction opposite to the first flow direction; a first refrigerant temperature measurement unit configured to measure, as first refrigerant temperature, temperature of the refrigerant flowing in the main heat exchange unit or between the main heat exchange unit and the pressure loss portion; a second refrigerant temperature measurement unit configured to measure, as second refrigerant temperature, temperature of the refrigerant flowing between the pressure loss portion and the expansion mechanism; and an operation control unit configured to control the flow direction switching mechanism to switch between normal operation of causing the refrigerant to flow in the first flow direction and defrost operation of causing the refrigerant to flow in the second flow direction, wherein the operation control unit has control modes for the defrost operation, including at least a first defrost control mode of terminating the defrost operation based on the first refrigerant temperature and a second defrost control mode of terminating the defrost operation based on the second refrigerant temperature, and the pressure loss portion is a branching portion of a refrigerant flow path in the first flow direction, characterized in that the operation control unit is configured to execute the defrost operation in the first defrost control mode when the second refrigerant temperature measured before the defrost operation starts is equal to or more than a first temperature (Trt). a refrigerant circuit including a compressor configured to compress a refrigerant, a first heat exchange unit having a main heat exchange unit, a sub heat exchange unit, and a pressure loss portion disposed on a flow path of the refrigerant between the main heat exchange unit and the sub heat exchange unit, a second heat exchange unit, an expansion mechanism disposed on the flow path of the refrigerant between the first heat exchange unit and the second heat exchange unit and configured to decompress the refrigerant, and a flow direction switching mechanism configured to switch a flow direction of the refrigerant discharged from the compressor, between a first flow direction of the refrigerant flowing in an order of the second heat exchange unit, the expansion mechanism, the sub heat exchange unit, the pressure loss portion, and the main heat exchange unit, and a second flow direction of the refrigerant flowing in a direction opposite to the first flow direction; a first refrigerant temperature measurement unit configured to measure, as first refrigerant temperature, temperature of the refrigerant flowing in the main heat exchange unit or between the main heat exchange unit and the pressure loss portion; a second refrigerant temperature measurement unit configured to measure, as second refrigerant temperature, temperature of the refrigerant flowing between the pressure loss portion and the expansion mechanism; and an operation control unit configured to control the flow direction switching mechanism to switch between normal operation of causing the refrigerant to flow in the first flow direction and defrost operation of causing the refrigerant to flow in the second flow direction, wherein the operation control unit has control modes for the defrost operation, including at least a first defrost control mode of terminating the defrost operation based on the first refrigerant temperature and a second defrost control mode of terminating the defrost operation based on the second refrigerant temperature, and the pressure loss portion is a branching portion of a refrigerant flow path in the first flow direction, characterized in that the operation control unit is configured to execute the defrost operation in the first defrost control mode when the second refrigerant temperature measured before the defrost operation starts is equal to or more than a first temperature (Trt).