PURPOSE: To improve comfortableness in driving, by making it a rule to adjust a capacity of a compression type refrigeration cycle so as to equalize a temperature of the dew point of conditioned air with that of cooling air to be spouted out from a vaporizer.

CONSTITUTION: A temperature of the dew point is computed by an arithmetic unit 33 for the temperature of the dew point through a temperature and humidity set by a temperature and humidity setting device 31 and is applied to a refrigeration cycle controller 34. A spouting out temperature 14 of an evaporator E is applied to the controller 34, which is compared with a temperature 33 of the dew point and refrigerating capacity is controlled by adjusting an opening of an expansion valve of a refigerating cycle 1 so that both temperature 14 and 33 becomes identical with each other. With this, a room temperature of a motor car can be adjusted comfortably and comfortableness in driving is.