PURPOSE: To obviate the trouble of operation and to pay regard to occupant's intention by automatically switching the air-conditioning operation back to control under a first controlling means when a prescribed period of time has elapsed after a desired air-conditioning operation is switched from a controlling state under the first controlling means to that under a second controlling means.

CONSTITUTION: A controller 21 is provided with a first controller, which controls various kinds of air conditioning operations for an air conditioning unit 1, based on the signals from sensors for a temperature of a heater core 15, temperatures of the air in the inside and the outside, and the quantity of solar radiation, and a second controller, which sets the quantity of various kinds of air conditioning operations by using a control panel 30 and, based on the values thus set, controls the first air conditioning unit 1. If a controlling state under the first controller is switched to that under a second controlling means associated with the setting by means of the control panel 30, when a prescribed period of time has elapsed, the system is automatically switched back to the control under the first controller. Accordingly, troublesomeness is removed from the main driving operation, and air conditioning operation in which occupant's intention is though much of can be carried out. In addition, even if the air conditioning state within the car is deviated from the prescribed conditions, the air conditioning state can be prevented from getting worse.