A facility management device manages communication data that is transmitted and received between remote controllers and an outdoor unit and/or indoor units. A temporary-memory controller stores communication data that was received by a communicator, and transmission-waveform data that was acquired by a transmission-waveform data acquirer for a specified amount of time in a temporary memory. An abnormality determiner determines whether or not there is abnormality in the communication data that is stored in the temporary memory. When it is determined that there is abnormality in the communication data stored in the temporary memory, a data copier stores all of the data that is stored in the temporary memory in an abnormal-data memory.