A structure for recognizing an article to be collected includes a recognition reference plane that is provided in a part of a holding base which holds the article to be collected with a predetermined positional relationship and that serves as a reference used for recognizing layout information about a position and an attitude of the holding base. The structure also includes a recognition indicator element which is placed on the recognition reference plane in such a way that an imaging tool captures an image of the recognition indicator element and which has four or more unit pattern marks at a predetermined positional relationship, in which each of the unit pattern marks is formed such that a density pattern sequentially changes with an increasing distance from a center position toward a periphery of the mark.