Abstract: Disclosed is an apparatus and method for sensing illumination by using an image sensor, in which a camera image sensor embedded in a wireless terminal is used to sense a peripheral illumination without using a conventional photo sensor. The apparatus includes: an image sensor for scanning an image with reference to each gain of Red, Green and Blue (RGB) to generate image data; a control unit for generating a light-emitting control signal or a light-emitting on/off signal with reference to the image data and the gain; and a light-emitting unit for adjusting an illumination of an internal light-emitting device or turning on/off the light-emitting device according to the light-emitting control signal or the light-emitting on/off signal.