PURPOSE: To provide the belt conveyor device which carries out mass conveyance at the high speed, is less in noise, vibration and environmental pollution, low in running cost and the cost of equipment, less in belt abrasion, and can smoothly recover fallen ores for transportation from a belt at the return side.

CONSTITUTION: In the air floating type belt conveyor which allows a belt to float by compressed air, the lower inner surface of a horizontal cylindrical pipe 10P is made to be the movable support trough 10 of a belt la at the carrier side, and the upper outer surface of the cylindrical pipe 10P is made to be the movable support trough 20 of a belt 1b at the return side. Air injection ports 10a and 10b and air ducts 12 and 22 for compressed air are disposed at the center sections of the movable support troughs 10 and 20 respectively, paired right and left opening sections 10A are provided for the sides of the cylindrical pipe 10P, and a fallen ore chute 7a is mounted therein.