1. An article estimating apparatus comprising: an article sensing unit that detects information of positions of a plurality of articles located in environmental space; a hand sensing unit that detects information of a position of a hand of a person that exists in the environmental space; a holding-state determination processing unit that determines a positional relationship between the information of the position of the article and the information of the position of the hand, respectively detected by the article sensing unit and the hand sensing unit, as a holding state of the article by the hand; and an article estimating unit that estimates an article whose ID corresponds to the information of the holding state determined by the holding-state determination processing unit as the article held by the person, based upon a holding-state registering database in which the holding state of each article by the person is registered as a positional relationship between the article and the hand of the person, for each ID of the article.