A heat pump device that collects heat both air and geothermal heat sources, and a controller determines, by comparing the temperature of an additional heat source and the current refrigerant temperature, whether or not to switch to simultaneous operation when there is insufficient capacity during single operation. During heating operation, the operation is switched to simultaneous operation if the temperature of the additional heat source is greater than the current refrigerant temperature, and single operation is continued if the temperature of the additional heat source is no greater than the current refrigerant temperature. As another determination method for during heating operation, the refrigerant temperature after addition of geothermal heat source is estimated and the heat pump is switched to simultaneous operation if the estimated refrigerant temperature is greater than the current refrigerant temperature. Single operation is continued if the estimated refrigerant temperature is no greater than the current refrigerant temperature.