To provide a miniaturized humidity control air-conditioning system for an automobile capable of reducing humidity control load of a car air conditioner.

In the humidity control air-conditioning system for the automobile, the car air conditioner 14 provided with a heater part 5 for circulating engine cooling water and a coolant evaporator 7 for evaporating the coolant; and a desiccant rotor comprising an adsorption area 8 for performing dehumidification of circulation air built-in with an adsorbent and a reproduction area 6 for performing moistening of circulation air are combined, and after outside air and/or indoor air are humidity-controlled, it is fed into the vehicle as feeding air. When a compressor of the car air conditioner 14 is in the operation state, it is made to a flow path in which it is circulated through the heater part 5 for circulating the engine cooling water, the reproduction area 6 of the desiccant rotor, the coolant evaporator 7 and the adsorption area 8 of the desiccant rotor in the order.