An electronic device packaging structure, in which a plurality of electronic circuit packages are arrayed on one side of a back panel with their signal input/output terminals projecting out onto the other side of the panel and each connected to one end of one of plural wiring cables. The other ends of the wiring cables are connected to relay connectors, which are fixed to a common frame, constituting a back panel system. A pair of such back panel systems are detachably coupled together via the relay connectors.