A surgical sealant comprising a first agent containing hydrophobized cold water fish-derived gelatin and a second agent containing a water-soluble crosslinking molecule, wherein the water-soluble crosslinking molecule has two or more active ester groups It is at least one selected from the group consisting of polybasic acids, acid anhydrides and aldehyde compounds having two or more aldehyde groups, and the hydrophobized cold water fish-derived gelatin is at least one amino group in the side chain of the cold water fish-derived gelatin. Part is gelatin substituted with a hydrophobic group, and the hydrophobic group has a substitution rate (number of moles of hydrophobic groups / (total number of moles of hydrophobic groups and reactive amino groups in gelatin) × 100) A surgical sealant characterized in that is a straight-chain aliphatic group having 8 to 18 carbon atoms and 3 to 20 mol%.疎水化冷水魚由来ゼラチンを含む第１剤と、水溶性架橋用分子を含む第２剤とからなる外科用シーラントであって、前記水溶性架橋用分子は、２個以上の活性エステル基を有する多塩基酸、酸無水物及び２個以上のアルデヒド基を有するアルデヒド化合物からなる群より選ばれる少なくとも一種であり、前記疎水化冷水魚由来ゼラチンは冷水魚由来ゼラチンの側鎖のアミノ基の少なくとも一部が疎水性基で置換されたゼラチンであり、前記疎水性基が、置換率（疎水性基のモル数／（疎水性基とゼラチン中の反応性アミノ基との合計モル数）×１００）が３～２０モル％の、炭素数８～１８の直鎖脂肪族基である、ことを特徴とする外科用シーラント。
