PURPOSE: To eliminate meandering or eccentric traveling of a conveyor belt by froming a carrier supporting base frame in such a manner that a fixed frame is coupled at its both ends in a flexible manner with slide frames each one end of which is supported in a freely movable manner in vertical direction by means of a spring.

CONSTITUTION: A base frame B, which supports a revolving carrier part A by a shaft, consists of both a fixed frame 4 and a pair of slide frames 5 and 5, each one end of which is inserted into the fixed frame 4 and coupled with the frame 4 in a slidable manner by means of a bolt 7 and a nut 8. And the other ends of the slide frames 5 and 5 are supported by a spring 16 so that they can freely move up and down in a bearing bracket C. This spring 16 is adjusted by means of an adjusting bolt 17 so that bolt tension is fully applied on carrier rollers a, a, and b, as well as the height of the carrier part A is determined. With this constitution, meandering or eccentric traveling of the conveyor belt can be prevented regardless of presense or absence of a load.