A method for preparing a decellularized tissue-based hydrogel with maximized ability of preserving various tissue-derived proteins, growth factors and cytokines by using a supercritical fluid-organic solvent system through (a) a step of decellularizing a biological tissue by bringing the same to contact with a supercritical fluid and an organic solvent at the same time； (b) a step of washing the decellularized tissue； (c) a step of preparing a decellularized tissue solution by mixing the washed decellularized tissue with one selected from an enzyme solution, an acidic solution and a mixture thereof； (d) a step of titrating the decellularized tissue solution to pH 5.5-7.8 by treating with a basic solution； and (e) a step of allowing the titrated decellularized tissue solution to stand at 30-40° C. and utilizing the same as a tissue engineering material with improved angiogenesis and tissue regeneration abilities.
