An article transport system with few missed detections, and a controller used in the system. The system includes: a conveyor that sequentially transports plural workpieces; a conveyor sensor that obtains conveyance operation information of the conveyor; an arrival sensor that senses the arrival of each workpiece; a camera that captures an image of each workpiece; a position detection processing section that detects the workpiece from the image, and identifies a position of the workpiece on the conveyor; a movement distance designation section that designates first and second movement distances; an image capturing control section that controls the camera to capture an image of the workpiece upon the conveyor advancing by the first movement distance after the arrival of the workpiece has been sensed, and each time the conveyor advances by the second movement distance; and a number designation section that designates an upper limit number for the detection process.