We established a new method using latex particles that adsorbed secondary antibody to detect the antigen on single fiber. Single fiber sample fixed on slide glass with double-sided adhesion tape was blocked by 4% Block-Ace, and reacted with 50- or 100-fold diluted primary antibody. The secondary antibody that adsorbed to latex particles captured the primary antibody combined with antigen on the fiber. Positive reaction was observed clearly on the fiber sample as adhesion of latex particles, and no reaction was observed in negative cases. It was possible to detect maximally 1,000-fold diluted saliva and 10,000-fold diluted semen on single fiber by this method. This method was able to be applied to ABO blood grouping as well. Moreover, we succeeded in simultaneous detection of antigen from body fluid and ABO blood-group substances, using different color of latex particle adsorbing each of secondary antibodies. Quality of latex particles adsorbing secondary antibody had been unchanged for at least three months since latex reagent was prepared. This method was able to be applied to forensic examination such as a test of aged body fluid stain and very small amount of body fluid stain. Therefore, it was suggested that this method has wide applicability and is useful for forensic science examination.