The present invention minimizes any strength reduction or tissue degeneration from before treatment, even when a drying treatment or sterilization treatment is carried out, for tissue comprising bio-derived components and the like. More specifically, biological tissue is immersed in a trehalose solution and shaken, thereby impregnating the biological tissue with the trehalose solution. The trehalose solution used herein is one obtained by dissolving trehalose in a phosphate-buffered physiological saline, the concentration of trehalose preferably being in the range of 20-35 wt%. Thereafter, a drying treatment for the biological tissue is carried out to remove moisture in the biological tissue, and a sterilization treatment for the tissue by ethylene oxide gas sterilization is carried out.
