There is provided a tissue adhesive to be applied to a tissue by mixing an adhesive component including an aqueous solution of a fish-derived gelatin with a curable component including an aqueous solution of a water-soluble crosslinking reagent, wherein the water-soluble crosslinking reagent has an amide linkage or an ethylene glycol unit or a sugar chain in the molecular main chain thereof and has two or more of an active ester group or an acid anhydride or an aldehyde group.
