The invention provides a multi-room air conditioning apparatus, which is capable of reducing loss of time from transmission of indoor machine operation signals to startup of frozen circulation, and quickly starting cooling and heating. If an operation command is received from any of the indoor units when the initialization of the corresponding electronic expansion valves is not completed. First, initialization is performed on the electronic expansion valve corresponding to the indoor unit which has issued an operation command. When the initialization has been performed on the electronic expansion valves corresponding to all of the indoor units which have issued an operation command, the flow proceeds to a processing step for a compressor. Then, the electronic expansion valves which have been initialized are adjusted to a predetermined operational opening degree. After this step is completed, the electronic expansion vales corresponding indoor units which have issued no operation command and whose initialization has not been completed are initialized and adjusted to a predetermined opening degree. This leads to a reduced loss of time until the compressor is activated after the electronic expansion valves are initialized.