There is provided a bioabsorbable peptide tissue occluding agent that can be applied to large mammals including humans, the peptide tissue occluding agent being obtained by artificial synthesis to avoid concerns of infection by viruses and the like. The tissue occluding agent contains a peptide, wherein the peptide is an amphiphilic peptide having 8-200 amino acid residues with the hydrophilic amino acids and hydrophobic amino acids alternately bonded, and is a self-assembling peptide exhibiting a β-structure in aqueous solution in the presence of physiological pH and/or a cation.