<p>It is possible to provide an input device capable of rapidly selecting and confirming an input character with simple operation without changing the group configuration of the numbers and characters fixed to the push buttons already widely spread as input devices of numbers and characters of a mobile device such as a mobile telephone and a mobile terminal. The input device includes: two key groups formed by keys 11 to 20, to each of which a plurality of character data are assigned and which are arranged in left and right rows; an auxiliary display (21) used when a first signal is inputted by one of the keys 11 to 20, for displaying the plurality of character data assigned to the key in a tandem so as to correspond to the key arrangement of the opposite key group at the left or the right side; and a control unit (30) used when a second signal is inputted by one of the keys of the key group of the opposite side after the first signal is inputted by one of the keys 11 to 20, for inputting the character data corresponding to the key which has inputted the second signal according to the arrangement of the plurality of character data displayed in the auxiliary display (21).</p>
