A coupling member comprising: a sliding member (62,64,82,84) having one axial direction end portion that is configured to be coupled to a first attachment portion provided at a first attachment that is adapted to be mounted to one of a maxilla or a mandible; and a sleeve (60,80) having one axial direction end portion that is configured to be coupled to a second attachment portion provided at a second attachment that is adapted to be mounted to the other of the maxilla and the mandible, the sliding member (62,64,82,84) being inserted into the sleeve (60,80) so as to be slidable, and a restricting section (66A,66B,86A,86B) being formed at the sleeve (60,80) between two axial direction end portions of the sleeve (60,80) so as to restrict sliding of the sliding member (62,64,82,84) in both directions along an axial direction of the sliding member (62,64,82,84), the sliding member (62,64,82,84) is configured by a rod (64,84) and a tube shaped engagement member (62,82), the rod (64,84) having said one axial direction end portion to be-coupled to the first attachment portion and being formed with a screw portion (64A,84A) at another axial direction end portion, and the tube shaped engagement member (62,82) having a screw receiving portion (62A,82A) formed at an inner peripheral face of one axial direction end portion of the tube shaped engagement member (62,82), into which the screw portion (64A,84A) of the rod (64,84) is screwed, wherein, one axial direction end portion of the sleeve (60,80) is open, and an insertion space is formed at another axial direction end portion of the tube shaped engagement member (62,82) for inserting a tool therein, characterized in that the restricting section is configured by narrow diameter portions (66A,66B, 86A,86B) formed at an inner peripheral face of the sleeve (60,80), between the two axial direction end portions thereof, and a wider diameter portion (68,88) is formed at the tube shaped engagement member (62,82) so as to abut the narrow diameter portions (66A,66B, 86A,86B), the wider diameter portion (68,88) being slidable between the narrow diameter portions (66A,66B,86A,86B), the tube-shaped engagement member (62,82) is configured to be rotated with respect to the rod (64,84), by the tool that is inserted into the insertion space, such that a length of the sliding member (62,64,82,84) (42, 44) is adjustable. a sliding member (62,64,82,84) having one axial direction end portion that is configured to be coupled to a first attachment portion provided at a first attachment that is adapted to be mounted to one of a maxilla or a mandible; and a sleeve (60,80) having one axial direction end portion that is configured to be coupled to a second attachment portion provided at a second attachment that is adapted to be mounted to the other of the maxilla and the mandible, the sliding member (62,64,82,84) being inserted into the sleeve (60,80) so as to be slidable, and a restricting section (66A,66B,86A,86B) being formed at the sleeve (60,80) between two axial direction end portions of the sleeve (60,80) so as to restrict sliding of the sliding member (62,64,82,84) in both directions along an axial direction of the sliding member (62,64,82,84), the sliding member (62,64,82,84) is configured by a rod (64,84) and a tube shaped engagement member (62,82), the rod (64,84) having said one axial direction end portion to be-coupled to the first attachment portion and being formed with a screw portion (64A,84A) at another axial direction end portion, and the tube shaped engagement member (62,82) having a screw receiving portion (62A,82A) formed at an inner peripheral face of one axial direction end portion of the tube shaped engagement member (62,82), into which the screw portion (64A,84A) of the rod (64,84) is screwed, wherein, one axial direction end portion of the sleeve (60,80) is open, and an insertion space is formed at another axial direction end portion of the tube shaped engagement member (62,82) for inserting a tool therein, characterized in that the restricting section is configured by narrow diameter portions (66A,66B, 86A,86B) formed at an inner peripheral face of the sleeve (60,80), between the two axial direction end portions thereof, and a wider diameter portion (68,88) is formed at the tube shaped engagement member (62,82) so as to abut the narrow diameter portions (66A,66B, 86A,86B), the wider diameter portion (68,88) being slidable between the narrow diameter portions (66A,66B,86A,86B), the tube-shaped engagement member (62,82) is configured to be rotated with respect to the rod (64,84), by the tool that is inserted into the insertion space, such that a length of the sliding member (62,64,82,84) (42, 44) is adjustable.