into which a turning tool is inserted for advancing the key ring 3 in the lag screw set and a retaining projection 4 4 the technical scope of this invention is not limited to the above described embodiment and various modifications can be made without departing from the gist of the invention the second embodiment of the present invention will now be described with reference to fig1 19 20 21 22 23 24 and 25 fig1 is a general configuration diagram of a master screw type screw apparatus for a lag screw set 17 according to the first embodiment as shown in this figure in the screw apparatus of the current embodiment a frame 11 and a nail 16 in accordance with a conventional art are used fig1 is a general view of the frame 11 fig2 is a general view of a stationary receiving boss 12 having a master screw female thread fig2 is a general view of a master screw driving knob 13 having a master screw male thread fig2 illustrates a general view of a connecting pin 14 that interrupts and establishes a connection between the master screw driving knob 13 and a lag screw driving sleeve 15 a general view of the lag screw driving sleeve 15 and a general view of a conventional art nail 16 are respectively shown in fig2 and 24 fig2 is a general view of the lag screw set.