A vehicle air-conditioning apparatus includes a refrigeration cycle that performs air-conditioning in a vehicle interior of a vehicle; a controller that includes a plurality of operation modes with different continuous operation times for a compressor, and that selects one operation mode from among the plurality of operation modes according to an air-conditioning load in the vehicle interior and executes the one operation mode, during travel operation of the vehicle; a storage unit; and a fault diagnosis unit. The fault diagnosis unit performs, during travel operation of the vehicle, fault diagnosis for the refrigeration cycle, after the high-load operation mode from among the plurality of operation modes, in which the continuous operation time is equal to or longer than a time that is set in advance is selected and executed by the controller at the timing stored in advance in the storage unit and while the refrigeration cycle is stable.