A method for labeling an object, which is effective when multiple types of labels are given as necessary even to a very small object such as a fine particulate substrate for use in fixation of biological substances such as probe molecules or nucleic acid primers that are used for a bioassay is provided. Further, an object given the labels is provided. Multiple types of labels can be given as necessary even to very small objects by using materials for labeling prepared in accordance with the composition condition of contained atoms corresponding to at least binary system n-digit numerical value information using a plurality of types (n types) of atoms selected beforehand as part of materials constituting the object, and presence/absence of the selected individual atoms contained or the level of the contents thereof. Further, the bioassay can be performed by the object labeled by the labeling method.