Abstract: A mat comprising a cushion base having a plurality of block plates each having cushion property and foldably connected together. A cushion member covers the upper surface of the cushion base, and the cushion base and the cushion member are detachably connected. The block plates are connected together at adjacent upper surfaces thereof and movably foldable about a centrally disposed fold line and a plurality of parallel transverse fold lines intersecting the longitudinal fold line. The fold lines are formed by slots which facilitate separation of the sehments when folded.