Abstract: A method for applying electromagnetic wave and ultrasonic wave therapies is provided. According to the method, a material simulating a living tissue is applied and pressed onto a surface of a human body so that the material is intimately contacted with the body surface with substantially no spaces present therebetween. Electromagnetic or ultrasonic wave is generated and irradiated to the body through the material. The material comprises a hydrogel having a high water content. The hydrogel is prepared by the steps of casting an aqueous polyvinyl alcohol solution into a mold, cooling the cast aqueous solution to obtain a cooled frozen mass and thawing the cooled frozen mass. The cooling and thawing steps may be repeated up to eight cycles. The hydrogel is also prepared by subjecting the cooled frozen mass to a partial dehydration step in vacuum.