PROBLEM TO BE SOLVED: To provide a nanoparticle having a natural product which is tannic acid and animal proteins as base materials.SOLUTION: There is provided a nanoparticle containing 0.1 wt.% or more of tannic acid as a solid component and 0.1 wt.% or more of at least one kind of animal protein selected from gelatin, collagen and decomposition products thereof and having weight ratio of the solid component of tannic acid and the solid component of animal protein (animal protein/tannic acid) of 0.05 to 8.0 and average particle diameter of 10 to 100 nm.SELECTED DRAWING: None