1. An article recognition apparatus comprising: a marker having four or more unit pattern marks which are provided at a predetermined positional relationship on an article to be recognized and which are formed in such a way that a density pattern sequentially changes from a center position to a periphery of the pattern marker; an imaging tool that is disposed opposite the article to be recognized and that captures an image of the marker; a supporting mechanism that supports the imaging tool so as to enable setting of the imaging tool at least at a non-face-up measurement position where an imaging plane of the imaging tool does not directly face up a surface of the marker provided on the article to be recognized and in a view field range of the imaging tool; and a layout information recognition block that recognizes layout information about a position and an attitude of the article to be recognized by use of at least imaging information about the marker whose image has been captured by the imaging tool placed at the non-face-up measurement position.