PROBLEM TO BE SOLVED: To improve the slip of the underfloor grounding surface of sound insulating floor material by covering the back of a base with a cushion made of synthetic-resin foam, and covering the underfloor grounding surface of the cushion with a synthetic resin. SOLUTION: A number of grooves 14 for increasing sound insulating effects are provided on the back of a base 11 made of a plate-shaped material such as plywood. The base 11 is covered on its back via an adhesive with a cushion 12 made from synthetic-resin foam such as polyurethane or polypropylene. The underfloor grounding surface of the cushion 12 is coated with a synthetic resin 13 such as polyester or acrylic to provide sound insulating flooring 10. Thus the coefficient of friction between the flooring and an object 15 placed thereon is made smaller to make it possible to provide an improved slip.