Provided are an apparatus and method for detecting an occluded face and an apparatus and method for discriminating an illegal user using the same. The apparatus for detecting an occluded face includes a smoothing unit, a region division unit, a first region detection unit, a second region detection unit, and a decision unit. The smoothing unit smoothes a facial region. The region division unit divides the smoothed facial region into a first region and a second region. The first region detection unit generates a first region detection result by detecting whether the first region is an occluded region. The second region detection unit generates a second region detection result by detecting whether the first region is an occluded region. The decision unit decides whether the facial region is an occluded face based on the first region detection result and the second region detection result.