A radiator (19; 50; 60; 65; 70) which radiates heat of refrigerant boosted up to supercritical pressure, comprising: a plurality of fin plates extending in a vertical direction and arranged at a predetermined interval; and a plurality of refrigerant channels (34A, 34B, 34C) formed in parallel by a heat transfer tube bundle inserted into the fin plates in multiple stages, a plurality of heat exchange units (45, 46), the radiator being vertically divided, wherein each of the plurality of refrigerant channels (34A, 34B, 34C) includes an inlet heat transfer tube (40A, 40B, 40C) disposed at an upper portion of the fin plates, an outlet heat transfer tube (42A, 42B, 42C) disposed at a lower portion of the fin plates, and a plurality of intermediate heat transfer tubes (41A1, 41A2, 41B1, 41B2, 41C1, 41C2) disposed between the inlet heat transfer tube (40A, 40B, 40C) and the outlet heat transfer tube (42A, 42B, 42C), wherein each of the refrigerant channels (34A, 34B, 34C) includes a plurality of first intermediate heat transfer tubes (41A1, 41B1, 41C1) connected to the inlet heat transfer tube (40A, 40B, 40C), a plurality of second intermediate heat transfer tubes (41A2, 41B2, 41C2) connected to the outlet heat transfer tube (42A, 42B, 42C), wherein each of the plurality of heat exchange units (45, 46) includes an upper heat exchange unit and a lower heat exchange unit which is disposed below the upper heat exchange unit, the upper heat exchange unit and the lower heat exchange unit being plural sections divided in a height direction, wherein the first intermediate heat transfer tubes (41A1) and the inlet heat transfer tube of each of the plurality of the refrigerant channels (34A, 34B, 34C) are disposed at the upper heat exchange unit, and the second intermediate heat transfer tubes (41A2) and the outlet heat transfer tube of each of the plurality of the refrigerant channels (34A, 34B, 34C) are disposed at the lower heat exchange unit, wherein the refrigerant sequentially flows from an upper heat exchange unit to a lower heat exchange unit in each of the refrigerant channels (34A, 34B, 34C), and characterised in that each of the refrigerant channels (34A, 34B, 34C) includes an intermediate header connected to all of the first intermediate heat transfer tubes (41A1, 41B1, 41C1) and the second intermediate heat transfer tubes (41A2, 41B2, 41C2) of the respective refrigerant channels (34A, 34B, 34C). a plurality of fin plates extending in a vertical direction and arranged at a predetermined interval; and a plurality of refrigerant channels (34A, 34B, 34C) formed in parallel by a heat transfer tube bundle inserted into the fin plates in multiple stages, a plurality of heat exchange units (45, 46), the radiator being vertically divided, wherein each of the plurality of refrigerant channels (34A, 34B, 34C) includes an inlet heat transfer tube (40A, 40B, 40C) disposed at an upper portion of the fin plates, an outlet heat transfer tube (42A, 42B, 42C) disposed at a lower portion of the fin plates, and a plurality of intermediate heat transfer tubes (41A1, 41A2, 41B1, 41B2, 41C1, 41C2) disposed between the inlet heat transfer tube (40A, 40B, 40C) and the outlet heat transfer tube (42A, 42B, 42C), wherein each of the refrigerant channels (34A, 34B, 34C) includes a plurality of first intermediate heat transfer tubes (41A1, 41B1, 41C1) connected to the inlet heat transfer tube (40A, 40B, 40C), a plurality of second intermediate heat transfer tubes (41A2, 41B2, 41C2) connected to the outlet heat transfer tube (42A, 42B, 42C), wherein each of the plurality of heat exchange units (45, 46) includes an upper heat exchange unit and a lower heat exchange unit which is disposed below the upper heat exchange unit, the upper heat exchange unit and the lower heat exchange unit being plural sections divided in a height direction, wherein the first intermediate heat transfer tubes (41A1) and the inlet heat transfer tube of each of the plurality of the refrigerant channels (34A, 34B, 34C) are disposed at the upper heat exchange unit, and the second intermediate heat transfer tubes (41A2) and the outlet heat transfer tube of each of the plurality of the refrigerant channels (34A, 34B, 34C) are disposed at the lower heat exchange unit, wherein the refrigerant sequentially flows from an upper heat exchange unit to a lower heat exchange unit in each of the refrigerant channels (34A, 34B, 34C), and characterised in that each of the refrigerant channels (34A, 34B, 34C) includes an intermediate header connected to all of the first intermediate heat transfer tubes (41A1, 41B1, 41C1) and the second intermediate heat transfer tubes (41A2, 41B2, 41C2) of the respective refrigerant channels (34A, 34B, 34C).