Wound bed preparation in a skin wound area can be carried out by using a hydrogel sheet, wherein the hydrogel sheet is prepared by spreading a hydrogel containing a water-soluble polymer, glycerin, and water on a two-layered laminated film consisting of a polyurethane film and a hydrophobic fiber and the moisture permeability of the hydrogel sheet is 200-2000 (g/m 2 /24 h).