PROBLEM TO BE SOLVED: To provide a peptide tissue block agent which is a biological absorption type capable of being applied to a large sized mammal including human being, the peptide tissue block agent being formed of artificial synthetic without anxiety of infectivity due to virus or the like.SOLUTION: The peptide tissue block agent including peptide is provided, the peptide has amphiphilic property in which hydrophilic amino acid and hydrophobic amino acid are alternately coupled, and 8-200 of amino acid residue is included, and under presence of physiological pH and/or cation, the self-assembly peptide exhibits a &bgr；-structure in solution.【課題】ヒトを含む大型哺乳動物に適用可能な生体吸収性のペプチド組織閉塞剤であって、ウイルスなどの感染性の懸念のない人工合成によるペプチド組織閉塞剤の提供。【解決手段】ペプチドを含有する組織閉塞剤であって、該ペプチドが、親水性アミノ酸と疎水性アミノ酸とが交互に結合し、アミノ酸残基８～２００を有する両親媒性のペプチドであり、生理的ｐＨおよび／または陽イオンの存在下、水溶液中でβ構造を示す自己組織化ペプチドである組織閉塞剤。【選択図】なし
