PURPOSE: To reduce the traveling noise of door rollers and increase durability by putting the door rollers provided at the top of a movable door slidably on a rail set along the upper part of an opened frame to travel guide bodies integrated with traveling wheels.

CONSTITUTION: Traveling wheels contact a rail surface, and travel on the rail surface while receiving the load of a movable door (a). Also guide wheels integrated with the traveling wheels are rotated with the rail held between flanges provided on both sides of the wheels from both sides to guide the traveling wheels traveling along the rail. In this case, the outer periphery of the wheels can be made in contact with or separated from the rail surface, and the outer diameter of the wheels including the flange can be reduced more than the traveling wheel. Also a door roller (c) is composed of a traveling wheel and a guide body, and the guide body is slid holding the rail from both sides when the traveling wheels travel to guide the traveling wheels along the rail. Thus the outer diameter of the traveling wheels can be increased to increase traveling noise and wear-resistant property.