PURPOSE: To allow the to execute translation processing to obtain a translated sentence closer to an original sentence without need of specifying an expert field in response to the content of the original sentence in the translated word selection device in the machine translation system.

CONSTITUTION: Original data stored in a data file 12 are read by a work station 11, the data are subject to syntax analysis, whether or not a translated word for each syntax is in existence in each of expert term dictionaries 15a-15e is checked via a translation system 13, any of translated word check counters 14a-14e corresponding to a dictionary in which the translated word is in existence is counted up, the selection priority of each of the expert term dictionaries 15a-15e is set depending on the quantity of count data in the translated word check counters 14a-14e, any of the expert term dictionaries 15a-15e is selected and retrieved for the translated word corresponding to translated document data according to the setting priority when the actual translation is processed.