Abstract: Safety clasp for the string of the footwear comprises a fastening member and a knot member having a lower portion, an extending portion and a head, the fastening member comprising a tube having two bores, a compression spring within the tube, two pins at both ends of the tube each having a bore corresponding to that of the tube, and a mount having a perforation corresponding to the head and the extending portion in cross section so as to detachably receive the knot member thereupon, whereby a permanent and adjustable knot is obtainable by: passing one free end of the string of the footwear through the bores of the tube and those of the pins; second, passing the other free end thereof correspondingly in the same manner as the first step; finally, passing both free ends thereof in an opposite direction through the hole of the lower portion of the knot member.