One end portion of a front-rear adjustment member 17 is disposed in a door-side mounting member 3 such that the front-rear adjustment member 17 is rotatable about a second shaft 12. An adjustment screw (not shown) having an axis thereof oriented in the left-right direction is provided in the door-side mounting member. The adjustment screw is threadedly engaged with the other end portion of the front-rear adjustment member 17. After the adjustment screw is rotated in normal and reverse directions, thereby rotating the front-rear adjustment member 17 as appropriate, a connecting arm 13 is rotated about a first shaft 11 so as to cancel out the rotation of the front-rear adjustment member 17.