An apparatus for unloading blocks that are stacked on pallets and have flat separators interposed between the blocks is provided. The apparatus has a three-dimensionally controlled and movable pick-up head on which is disposed an approximately horizontally oriented insertion tool that terminates in a pointed insertion tip. The insertion tool is adapted by means of a horizontal movement to extend below a respectively to be removed block of blanks. In order to recognize an improperly taken up block of blanks prior to further processing thereof, a sensor unit is provided that cooperates with a reflective element that is disposed on the underside of the insertion tool. This makes it possible to inspect if a portion of the bottom blank is disposed below the insertion tool. A block of blanks that has been recognized as improper is initially separated out.