To tighten a full length screw bolt without crushing a screw thread.

An inner side of a device 1 is formed into a taper shape, and an outer side of a female screw 4 divided into two parts is formed into a taper shape and is internally provided in the device 1 so as to slide the inner side of the device 1. Grooves 3 and 5 are formed in the taper parts of the device 1 and the female screw 4 divided into two parts, a spring 9 is put on a bottom 8 of the device 1 and is internally provided in the device 1 after nipping springs 6 and 7 between the female screw 4 divided into two parts and it, and a pin 10 is inserted between the grooves 3 and 5 and is fastened by a plate spring 11. When the full length screw bolt 13 is inserted into the female screw 4 divided into two parts and the device 1 is pressed, the female screw 4 divided into two parts nip the full length screw bolt 13 because the inside is tapered, and when a hexagonal pin 14 is turned, the full length screw bolt 13 can be tightened. When removing it, the device 1 is pulled so that the female screw 4 divided into two parts is pressed by the spring 9, is opened, and is removed simply from the full length screw bolt 13.