Abstract: There are disclosed a natural peptide search in which a template reaction with the nucleus of a minute amount of amyloid ?-protein having undergone amyloid fibrosis is induced so as to form amyloid fibers, followed by fiber amount increase and amplification; designing and development of a novel artificial peptide which can be a substitute therefor; a method of amplifying the amyloid fibrosis of amyloid ?-protein with the use thereof and a reagent for use therein; and a method of detecting disease caused by amyloidosis and a reagent for use therein.