PURPOSE: To efficiently control a heat pump having an auxiliary heat source for softening an atmosphere in a closed space by holding curves parallel to each other in a first mode of operation and first operation curves at a minimum gradient in a second mode of operation, and regulating a gradient of the second curve to increase or decrease an operation of the auxiliary heat source.

CONSTITUTION: A thermostat means 21 has two stages. In a first mode of operation, a first stage and a second stage are operated to pick up a temperature between a night setback temperature and normal comfortable temperature in the state that separate heat pump ramp rate and auxiliary heat ramp rate can be operated together in parallel. The heat pump and auxiliary heat ramp rates are changed daily in response to conditions of a previous day. The heat pump 11 is controlled by the first stage of the means 21 and the auxiliary heat source 12 is controlled by the second stage of the means 21. The means 21 responds to an air temperature 31 and a wall temperature 30. And a closed space 17 responds to a combination of a weather 20 and heat supplied via a distributing circuit network 15 through a duct 16.