To provide a line-up device for a thin plate-like object to be conveyed in a conveying device capable of certainly lining up the rectangular thin plate- like object to be conveyed inclinedly conveyed in the direction perpendicular to the conveying direction by directing the direction thereof to a constant direction.

Since a traveling device 18 disposed at a predetermined position of a lower end guide member 16 has a speed different from a belt speed of a belt conveyor 1b for conveying a thin plate-like case 2, a rotation force is generated when the thin plate-like case 2 is contacted with a belt 20 of the traveling device 18 and one side of a lower end of the thin plate-like case 2 is urged to the lower end guide member 16. Thereby, the case 2 can be certainly lined up while the direction of the case is directed to a constant direction.