To provide a geothermal heat pump-type dry air conditioning system capable of saving energy by controlling the temperature and humidity of supplied air without reheating, and reducing equipment costs and operation costs for air conditioning.

This geothermal heat pump-type dry air conditioning system comprises an air conditioner 1 having a compression-type heat pump A applying a heat medium as a heat source, a heat source water circuit 3 for circulating the heat medium, an underground heat exchanger 4 connected with the heat source water circuit 3 and adjusting a temperature of the heat medium, and a variable air volume unit 5 capable of individually adjusting the air supply volume from the air conditioner 1. The heat pump A comprises an air supply-side heat exchanger 6 for processing the outside air to exchange heat of the outside air, and an air supply-side heat exchanger 7 for processing return air, to exchange heat of the return air. The heat pump A, a humidifier 9 for humidifying the outside air, and an air blower 10 for mixing the return air passing through the air supply-side heat exchanger 7 for processing return air, and the outside air passing through the air supply-side heat exchanger 6 for processing the outside air and the humidifier 9, are disposed in a casing 8 of the air conditioner 1.