PURPOSE: To execute the KANA (Japanese syllabary) to KANJI (Chinese character) conversion irrespective of whether a long vowel of a word of foreign origin exists or not by providing a long vowel detecting part and a long vowel adding part on a KANA to KANJI converter, and using a dictionary in which a long vowel of a KATAKANA (square form of Japanese syllabary) word in which whether a long vowel exists or not is unstable is eliminated.

CONSTITUTION: When reading of a KANA to be converted to a KANJI is inputted, it is stored in an input control part 12, and also, in the case it is detected by a long vowel detecting part 15 that a long vowel is contained in this reading, a reading train in which a long vowel is deleted is transferred to the input control part 12, and a position of the deleted long vowel is informed to a long vowel adding part 16. A dictionary retrieving part 13 retrieves a dictionary 14, and transfers the notation concerned to the input control part 12. The input control part 12 transfers the transferred notation to the long vowel adding part 16 and inserts the long vowel deleted by the long vowel detecting part 15 into its original position, and executes display and storage of the notation to a display device part 17 and a storage device part 18. In such a way, in the notation of a KATAKANA word containing a long vowel, reading in which whether a long vowel exists or not is unstable can be converted to KANA to a KATAKANA word irrespective of whether a long vowel exists or not.