PURPOSE: To enhance workability, when a door is supported by pivot receiving fittings that have been provided to the respective one ends of the upper and lower parts of the door, by projecting the head of the adjusting screw for fixing the fitting to the guide rail while inserting it from the front side of the base plate of the fitting.

CONSTITUTION: When pivot receiving fittings 10 for adjusting the clearances on both sides of a folding door 50 are adjusted, after the door has been closed, the adjusting screw 20 is loosened from the front side of the door 50 by means of a wrench 30. Then, after the fitting 10 has been moved to a proper position while seeing the degree of clearance of the door 50, the screw 20 is tightened by the wrench 30 for fixing the fitting 10 to a guide rail 64. Thereby, the adjustment of the door can be simply carried out from the frontside of the door at one time, and also the labor for repeatedly going in and out from a housing body for readjusting as before can be eliminated, and the efficiency of work can be enhanced.