The present invention provides a new stock control system that can grasp the stock status of objects to be controlled and is excellent in convenience. The stock control system of the present invention includes a shelf 10; a marker 11; an image acquisition unit 12; a storage unit; an analysis unit; and an alert unit. The shelf 10 is a shelf on which an object to be controlled 20 is placed. The marker 11 is disposed in the shelf 10 at a position where it is shielded from the image acquisition unit 12 due to the placed object to be controlled 20. The image acquisition unit 12 acquires an image of the marker 11. The storage unit updates and stores on-time stock information of the object to be controlled 20 placed on the shelf 10 based on sales information of the object to be controlled 20. The analysis unit analyzes, upon acquisition of the image of the marker 11 by the image acquisition unit 12, the on-time stock information in the storage unit. The alert unit outputs an alert according to an analysis result of the analysis unit.