1. A character input device comprising: dictionary means for storing input character or input character string and candidate character corresponding to the input character or candidate character string corresponding to the input character string; input means for entering characters or character string including a plurality of keys to which a plurality of characters are distributed, a conversion/next candidate key for designating character conversion and a decision key for deciding the designated conversion; output means for at least displaying and outputting candidate character or candidate character string obtained as the result of conversion; and character conversion means for obtaining candidate character or candidate character string by retrieving said dictionary leans, with respect to the input character or input character string entered from said input means, and for transmitting this candidate character or candidate character string to said output means.