PURPOSE: To simplify the structure in comparison with the former angular casing in such a way that the sectional shape of a casing of a trough conveyor to convey flour, etc. is formed circularly or elliptically.

CONSTITUTION: When a shaft 4 is driven by a geared motor, a chain 16 is turned in the direction as shown by arrows, objects to be conveyed which have been gradually thrown from an inlet port 19 are portioned out through a return housing 6 to the left and right coming into a feeding housing (a) through which the inlet port 19 is penetrated, the objects to be conveyed are conveyed through an attachment of a chain 16 which runs through the bottom part into a head part housing c, and further discharged through a discharge port 10. Since the housings (a), b are circularly or elleptically shaped in their sectional form, when manufacturing, it is enough only to cut the existing pipe material to the desired length, and to provide flanges for connecting them, and since the object to be conveyed runs of its own accord to the bottom part, there is not partial stangnancy.