character input apparatus includes : touch screen ; first keypad information database storing information on first keypad ; second keypad information database storing information on second keypad ; first keypad generation unit displaying the first keypad including character key on the touch screen during character input mode ; first key touch recognition unit acquiring character code corresponding to first key from the first keypad information database and invoking second keypad generation unit , when the first key is sensed on the first keypad ; the second keypad generation unit generating the second keypad including character keys related to the first key by invocation by the first key touch recognition unit , and displaying the second keypad on the touch screen ; and second key touch recognition unit acquiring character corresponding to touch movement action from the second keypad information database and displaying the character on the touch screen , when the touch movement action is sensed on the second keypad .