PURPOSE: To make it possible to convey a material such as grain with a high density by pneumatic conveyance under a generally used low pressure, by using a rotary feeder and an air lift pump in combination.

CONSTITUTION: Air under pressure fed from a blower 3 on operation flows through an air pipe 4 into an air lift pump 5 and then flows upward through a porous air filtrable plate 12 so that the air penetrates into a material to be conveyed, which has been accumulated on the plate 12, to float up the material. Therefore, the material is led along the surface of the plate inclined at a set angle, into the opening end part of a conveying pipe 6. The material to be conveyed ascends through the pipe 6 from the opening end part having been buried in the material, in a semi-float condition, and changes it direction, and therefore, the material is discharged horizontally from a discharge port 7 into a container 20 as a destination. Air containing dust, which has accompanied with the material so as to be discharged into the container 20, flows through suction ports 8 that are formed in parallel in the upper and lower parts of the discharge port 7, and through a return pipe 9 under suction force by the blower 3, and is compressed by the latter after being purified by a bag filter 10 so that it is reformed into conveying air which circulates through the system.