Abstract: A drug that inhibits aggregation of amyloid-?, which causes Alzheimer's disease and the like. The amyloid-?aggregation inhibitor is characterized by containing at least one of a peptide having an amino acid sequence of SEQ ID NO: 1 (GSGNR) or a peptide having an amino acid sequence of SEQ ID NO: 2 (GSGFK). A pharmaceutical composition for an amyloid-?aggregation disease is characterized by containing at least one of a peptide having an amino acid sequence of SEQ ID NO: 1 (GSGNR), and a peptide having an amino acid sequence of SEQ ID NO: 2 (GSGFK).