To provide an input/output device which transfers data from a line having a different transfer method and inputted data to a specified transfer destination or prints the data out.

This device is equipped with a transmission and reception part which is connected to a line network having a different data transfer method and sends and receives data to and from the connected line network, a print output part which outputs print data to a printer, an input/output part which inputs and outputs data, a storage part which stores data, an input/output control part which stores the storage part with the data inputted from the transmission and reception part and input/output part and outputs the data stored in the storage part to the transmission and reception part, input/output part, and print output part, an output conversion part which converts the data stored in the storage part to the format of data corresponding to the print output part, and an output management part which informs a transmission source that an error occurs to the output conversion part in such a case.