1. A method for recognizing a protrusion on a face, comprising: forming a first image of a target in a condition in which the target is lighted and a second image of the target in a condition in which the target is non-lighted to obtain two images of the target; detecting a face region from the first image and a face region of the second image from the second image, respectively; comparing the face regions detected from the first and second images; analyzing a change of contrast in the face regions; and determining a protruding degree of a face corresponding to the first and second images based on the result of the analyzing.