To provide an open-separation fitting insert which enables conveniently free insertion of a butterfly bar combinedly from right or left hand in a fastener chain having a slider with a stopper.

In a slider with a stopper, one end of a plate spring 17 bent roughly in U-shaped is fixed in an enclosed wall 21 provided on the front of a shell part 15, a stop pawl 30 is provided biased to the center of the other end to face a butterfly bar 3, and a pivot of a pull 16 with a cam part is inserted into an upper part of the stop pawl 30 to be pivoted. In the butterfly bar 3 in the open-separation fitting insert, an upper corner of a surface thereof facing a box bar 2 is notched to provide an avoid part 10 for avoiding locking of the stop pawl 30, and a recessed groove 9 is provided in the opposed surface to be fitted into a thread part 4 of the box bar 2. A claw stop part 5 is progressively provided at the top part of the butterfly bar 3. When the butterfly bar 3 is inserted into the box body 1, the stop pawl 30 is interposed between the top surface of the box bar 2 and the underside of the claw stop part 5. In the insertion of the butterfly bar 3 into the box body 1 from the right thereof, the stop pawl 30 slides over the avoid part 10, because in the insertion from the left, the stop pawl 30 has no relation with the butterfly bar 3 thereby enabling free insertion of the butterfly bar 3.