PURPOSE: To ensure a comfortable air quantity over a wide range of vehicle speed by making traveling wind bypass a blower means which becomes draft resistance and feeding same to a heating means while providing an air quantity regulating means which is controlled so as to bring an introduced air quantity close to a desired air quantity.

CONSTITUTION: In the traveling wind intake mechanism portion of an air conditioner, a traveling wind duct 7 for introducing outdoor air from a traveling wind intake port 5 bypassing a blower 6 is provided between the blower 6 and an evaporator 8 on the upper course side of a heater core 9. A traveling wind door 14 for regulating an introduced air quantity from the traveling wind duct 7 is provided on the traveling wind intake port 5 of the traveling wind duct 7 while providing an air velocity sensor 29 for measuring the air velocity of an introduced air inside the traveling wind duct 7. An introducing-passage switchover door 15 carries out the selection between the blower 6 and the traveling wind duct 7. The traveling wind door 14 is controlled so as to make an air quantity obtained from an air-velocity measured value a desired air quantity.