A loosening-proof screw fastening device, including at least one stop wheel on at least one of a plurality of contacting faces; the at least one stop wheel is rotatably assembled in a locating hole on said at least one contacting face with its stop tooth slightly protruded beyond the contacting face; upon application of a backward action force for loosening the fastening device a created torque will bring the at least one stop wheel into rotation and make a stop tooth of the at least one stop wheel protrude beyond the contacting face and penetrate into a surface closely opposed to the at least one contacting face for preventing the fastening device from loosening.