A mobile terminal including a case; a touch key mounted in a predetermined portion of the case and configured to generate touch type input data; a light source arranged on a back side of the touch key and configured to emit light; and a light diffusion unit configured to diffuse the light emitted from the light source and provide a backlight to the touch key. Further, the light diffusion unit includes a light guide part configured to guide the light emitted by the light source; an air gap arranged on the light guide part and configured to diffuse the light provided from the light guide part; and a diffuser arranged on the air gap and configured to diffuse the light provided from the air gap towards the touch key.