A method of waking up a device includes capturing an image by scanning a fingerprint pattern in a sleep mode; analyzing the captured image representing the scanned fingerprint pattern to obtain an amount of pixels in the captured image with respect to each brightness value; transforming the analyzed captured image into brightness distribution; operating the brightness distribution to obtain a feature value; and comparing the feature value with a pre-stored value, the device being woken up when the feature value is matched with the pre-stored value.