PURPOSE: To make it possible to surely guide a belt, by constituting a frame with a flat plate section for guiding the belt and bearing sections arranged on both sides of the flat plate section.

CONSTITUTION: In a frame 10, the upper parts of support rollers 25 disposed in support roller units 20 which are provided in a flat plate section 15, are projected from the upper surface of the frame 10. Each support roller unit 20 is composed of a support plate 21 and support rollers 25 provided at both ends of the support plate 21. In a conveying belt device 5 composed of the frame 10 and the support roller units 20 in combination, a belt 6 is stretched between a drive roller 7 and a driven roller 8, and is supported at the lower surface thereof by the support rollers 25 so that the belt is guided.