PURPOSE: To increase the durability of a belt for driving rollers of a roller conveyor and to increase the reliability and safety of its transmission.

CONSTITUTION: At least two guiding pulleys 7 are provided at the clearing part a belt to for a first and a second pulley 10, 11 arranged at one end and the other end of carrying pulleys 4 arranged below a roller group 3 for carrying cargoes. The belt runs on the guiding pulleys 7A, 7B, 7C with their backs faced outwardly one another. The travelling line between the pulleys of the belt are located on the crossing line crossing with the two rotary surfaces of the pulleys at their both the sides. In addition, angle of torsion per the unit length of the belt is controlled.