PURPOSE: To decrease the redundancy of information to be sent and to quicken the transmission speed and to make the use of line efficient by replacing a consecutive code in an original file based on a dictionary code table stored in a dictionary code file into an abbreviation code so as to generate abbreviation information.

CONSTITUTION: A control section 200 extracts all words in a document data stored in a memory 620 and stores them in a memory 640 for storing a dictionary code and counts the frequency of appearance of them. Then an abbreviation code is decided to each of the words stored in the memory 640 and a dictionary code list is generated corresponding to each word and the result is stored in the memory 640. When the storage of the abbreviation code is finished, while the content of the memory 640 is referenced, the document data stored in the memory 620 is converted sequentially into the abbreviation code based thereon and the code is stored in an abbreviation information storage memory 660. When the conversion is finished, a control section 280 converts the dictionary code list used for the conversion in the memory 640 and the abbreviation information stored in the memory 660 into a serial signal and outputs the signal to a MODEM 300.