Key inut apparatus using light emittion for displaying key input and light emittion method using the same

PURPOSE: A key input device using light emission for displaying key input and light emission is provided to easily detecting typographical errors by recognizing a pushed key by the light without observing input screen of a mobile device. CONSTITUTION: A key input device using light emission for displaying key input and light emission comprises: a key input unit(120) outputting key input signal when a specific key among a plurality of keys is pushed, and distinguishing the specific key by light; a control unit(130) outputting information about character and number to a display unit(110) corresponding with the key input signal and displaying the character corresponding with the specific key through a display unit. For longer time than the pushed time of the specific key, the specific key is distinguished by the light.