A vehicle air-conditioning apparatus includes a dehumidification means, which has a compressor and dehumidifies inside of the vehicle, a humidity calculation means, which calculates humidity in the vicinity of an inside surface of the windshield, and a determination means, which determines whether the windshield is fogged on the basis of comparison between the humidity and a predetermined value. A defogging operation for heightening dehumidifying performance of the dehumidification means is performed, when the determination means determines that the windshield is fogged in a state where the compressor is turned on. The dehumidifying performance of the dehumidification means is lowered or condition in which the defogging operation is started is made to be difficult in the next defogging operation, when the windshield is determined to be fogged and the defogging operation is not manually performed in a state where the compressor is turned off.