The present invention provides a method for rapidly clearing a biological tissue. According to the present invention, provided is a method for clearing a biological tissue, including the steps of: infiltrating the biological tissue with water-soluble ethylenically unsaturated monomers before, during or after fixing the biological tissue with a fixative, wherein the water-soluble ethylenically unsaturated monomers include at least a water-soluble ethylenically unsaturated monomer having an ionically dissociable group; polymerizing the water-soluble ethylenically unsaturated monomers to form a hydrogel in the fixed biological tissue; and removing a lipid from the fixed biological tissue.