Texts including required message are entered with a small number of keys such as those of a cellular telephone. In this case, a conversion table is unnecessary and the number of key operations is reduced. The number of input characters or input character strings composed by sequentially selecting one from a plurality of alphabets distributed to sequentially entered keys is relevant to the number of operation keys (N) raised to the number of distributed character (M) power (=NM) including meaningless characters or character strings and, with respect to these, character conversion is executed by referring to a dictionary means, through the operation of the conversion next candidate key. The dictionary means stores numeric strings and words of meaningful characters or character strings among the said characters and character strings.