A portable air conditioning apparatus includes a refrigerating circuit comprising a variable capacity compressor and a condenser cooled by water fed from a water tank and a flow of air generated by a fan device, an inverter for outputting a variable driving frequency to the compressor, and a control section for controlling the frequency of the inverter in response to an air conditioning load in a defined space. The control section has a frequency control function by which the driving frequency of the inverter is forcibly decreased irrespective of the air conditioning load to reduce the consumption of water at the condenser when an amount of water is detected to be below a prescribed value in the water tank.