The present invention suppresses the strength reduction or degeneration of a tissue after the tissue is dried and/or sterilized, for the tissue comprising biological components and the like. Specifically, biological tissue is immersed in a trehalose solution and shaken, thereby impregnating the biological tissue with the trehalose solution. The trehalose solution used here is one obtained by dissolving trehalose in a phosphate buffered saline, the concentration of trehalose being preferably in the range of 20 wt% to 35 wt%. Thereafter, the biological tissue is dried to remove moisture in the biological tissue, and sterilized with ethylene oxide gas.
