A character and function key input device comprises: a character button unit having character buttons, each of which is assigned to one or more characters of one or more languages or function key elements; a forward button which converts the character or function key element selected from among the characters or the function key elements into characters or function key elements assigned to the selected button or adjacent button in accordance with the dictionary order; and a backward button which converts the character or function key element selected from among the characters or the function key elements into characters or function key elements assigned to the selected button or adjacent button in accordance with the dictionary order, wherein said one or more characters or function key elements assigned to the character buttons are disposed adjacently to one other in the dictionary order, and the character or the function key element having the highest use frequency is used as a basic value. The dictionary order has a circulation configuration such that the first character or the first function key element appears again after the last character or the last function key element.