To inhibit the thickness of a sheet at a constant value, and to improve walking feeling while obtaining an excellent soundproofness by forming a striped bottom section to one surface of a foamed rubber.

A natural rubber composition is kneaded. The natural rubber composition is laminated on a nonwoven fabric by a calender in specified thickness. A striped bottom section is formed by pushing. The laminate is foamed at specified times in a chamber, and cooled. A PVC composition is kneaded, and laminated on the nonwoven fabric by the calender in specified thickness. The laminate is foamed at fixed times, and pushed instantaneously and a striped bottom section is formed. The pushed laminate is cooled. Accordingly, soundproof performance and walking feeling can be improved.