To provide a field dictionary forming device for supporting the formation of a field dictionary in which a translation dictionary by field adapted to the times is simplified and automated as much as possible, paying attention to a katakana word in Japanese in order to reduce the dictionary maintenance work.

In a special field dictionary for supporting mechanical translation, this device is connected to the Internet to read text information from a Japanese homepage related to a special field. The information is divided to languages by morpheme analysis, a katakana word, particularly, is extracted therefrom with its appearance frequency, and a precise translation is imparted to the katakana word.