Abstract: A coil spring 213 is sandwiched between a coil spring adjoining wall 202a of the female plug shell 202 and the edge of the large ring of the slide sleeve 203 and is held inside of the slide cover 215 in which the coil spring 213 can expand and contract freely. Sliding of the slide cover 215 in the positive direction of the x axis is restricted because the coil spring 213 or the slide sleeve 203 is adjacent to the coil spring adjoining wall 202a, and sliding in the negative direction of the x axis is restricted by a caulking 210. The caulking 210 caulks its bottom part, or the end part 215b which is placed at the opposite side of the opening part of the slide cover 215, to inside of the female plug 200. By applying this calking 210, problems described above can be solved.