A communication device reduces a processing time required at the time of mutually converting different wireless or wired communication protocol and improves a real-time property. The communication device includes two or more communication units which communicate with two or more external devices and a communication controller which processes communication data. The communication controller has table information that associates a communication path, a type of the communication unit, and conversion-info, and an input and output unit that inputs and outputs the table information. According to the added conversion-info, a conversion unit sequentially performs various conversion processes (protocol conversion, routing, communication quality evaluation, fragmentation/integration of communication interface, fragment/defragment process, frame multiplication/integration, and frequency setting).