To provide a mat preventing the occurrence of a stuffy phenomenon and effective for health maintenance by adjacently providing small wood pieces made of paulownia wood on the surface of a flexible sheet.

A paulownia plate 2 with a proper thickness is stuck via an adhesive to the surface of a flexible sheet 1 of vinyl leather or the like equal in size to a bed in advance. Only the paulownia plate 2 is cut into checkers with a cutter 3. Many small wood pieces 2a are formed on the surface of the flexible sheet 1 via the cutting by the cutter 3, and small gaps 5 are automatically formed by the cutter 3 between individual small wood pieces 2a thus formed. The occurrence of a stuffy phenomenon can be prevented, and a sleeping posture can be kept correct by proper deformation of the small wood pieces 2a.