This invention discloses a preserving agent for organs or tissue comprising (A) quercetin, and (B) at least one sugar selected from the group consisting of fructose and sucrose； a preserving solution for organs or tissue comprising the preserving agent； and a preservation method for organs or tissue comprising the step of immersing an organ or tissue in a liquid mixture comprising (A) quercetin, and (B) at least one sugar selected from the group consisting of fructose and sucrose.
