Abstract: Shoes with two sets of elastic nails on the sole are provided. When one wants to walk on snowy ground or ice, a key may be used to allow the two sets of nails to project from the sole to prevent sliding. If he wants to walk on the ground without snow or in a room, the key may be turned off and then the nail sets retract into the sole. This result is achieved by means of a structure which comprises a box with the shape similar to the sole. The box is installed between the insole and the sole. The box includes the body, a switching device, a moving board, two nail sets and a sole cover. When the switching device is turned, the moving board moves straight. The thicker part of the moving board to be inserted into the upper part of the nail set forces the nail set to project from the hole on the sole to constitute a pair of sliding-proof shoes. On the contrary, when the switching device is reversed, the nail set retracts into the sole so that a pair of common shoes results.