A heat medium relay device comprising: a housing having an interior partitioned into a first space, a second space, and a third space; a first heat exchanger provided in the second space, and configured to cause heat exchange to be performed between a primary heat medium and a secondary heat medium, the primary heat medium being in a cooled state and supplied from an outdoor unit; a first pump provided in the first space, and configured to pressurize the secondary heat medium subjected to the heat exchange at the first heat exchanger, and circulate the pressurized secondary heat medium between the first pump and at least one indoor unit; a second heat exchanger provided in the second space, and configured to cause heat exchange to be performed between the primary heat medium and the second heat medium, the primary heat medium being in a heated state and supplied from the outdoor unit; a second pump provided in the first space, and configured to pressurize the secondary heat medium subjected to the heat exchange at the second heat exchanger, and circulate the pressurized secondary heat medium between the second pump and the at least one indoor unit; and a valve block provided in the third space, the valve block including a plurality of valves to allow the secondary heat medium subjected to the heat exchange at the first heat exchanger and the secondary heat medium subjected to the heat exchange at the second heat exchanger to flow to the at least one indoor unit, characterized in that that the housing has a vertical cuboid shape, the second space is above the first space and the third space is above the second space, and the valve block is lighter in weight than each of the first heat exchanger, the first pump, the second heat exchanger, and the second pump. a housing having an interior partitioned into a first space, a second space, and a third space; a first heat exchanger provided in the second space, and configured to cause heat exchange to be performed between a primary heat medium and a secondary heat medium, the primary heat medium being in a cooled state and supplied from an outdoor unit; a first pump provided in the first space, and configured to pressurize the secondary heat medium subjected to the heat exchange at the first heat exchanger, and circulate the pressurized secondary heat medium between the first pump and at least one indoor unit; a second heat exchanger provided in the second space, and configured to cause heat exchange to be performed between the primary heat medium and the second heat medium, the primary heat medium being in a heated state and supplied from the outdoor unit; a second pump provided in the first space, and configured to pressurize the secondary heat medium subjected to the heat exchange at the second heat exchanger, and circulate the pressurized secondary heat medium between the second pump and the at least one indoor unit; and a valve block provided in the third space, the valve block including a plurality of valves to allow the secondary heat medium subjected to the heat exchange at the first heat exchanger and the secondary heat medium subjected to the heat exchange at the second heat exchanger to flow to the at least one indoor unit, characterized in that that the housing has a vertical cuboid shape, the second space is above the first space and the third space is above the second space, and the valve block is lighter in weight than each of the first heat exchanger, the first pump, the second heat exchanger, and the second pump.