PURPOSE: To securely convey an article, by providing horizontal conveyance mechanisms in a conveyor which is applied to a mail automatic processor or the like and vertically and horizontally carries the articles such as pallets for sheets of paper.

CONSTITUTION: A pallet circulation conveyor, which is installed behind an automatic reading and sorting machine with an automatic delivery function or the like, comprises a horizontal conveying portion 1 with pallet conveying passages 1aW1d provided at plural levels to convey pallets 4, a pallet returning passage 2 provided under behind the horizontal conveyance portion, an ascent lifter 3 for moving the pallets 4 from the returning passage to the upstream ends of the conveying passages, and a descent lifter 5 for moving the pallets from the downstream ends of the conveying passages 1bW1d into confluence at an extension of the downstream end of the conveying passage 1a. To construct the lifters 3, 5, horizontal conveyance mechanisms 10 for articles are provided on rests 8aW 8c, which are moved back and forth by rodless cylinders 7aW7c.