has an opening in one side of a body of the transfer nut lump housing 12 such that it allows the locking lever pressing part 13 to move towards the locking lever roller 18 the locking lever pressing part 13 is actuated such that when the transfer nut lump is transferred in the direction in which the sliding door is opened it is rotated together with the transfer nut lump so as to force the locking lever roller 18 to move thereby allowing the locking roller 16 to unlatched from the locking hook 20 the transfer nut support 14 has the shape of a right angled section in one side of the transfer nut lump thereby serving to support the transfer nut lump such that the transfer nut lump cannot rotate at a certain angle or more when the transfer nut lump is in the locked or opened state the locking lever 17 is connected with the transfer nut lump housing 12 by means of the locking lever hinge 26 so that it can be moved by a certain distance in the direction perpendicular from the advancing direction of the sliding door while rotating about the locking lever hinge specifically the locking lever may include the locking lever roller 18 and the locking roller 16 here the locking lever roller is designed such that when the transfer nut including the locking lever pressing part 13 is rotated it is brought into contact with the locking lever pressing part 13 to allow the locking lever 17 to be moved by a certain distance while being.