To provide a bed for Futon, Japanese style mattress, capable of preventing damp when laying out the Futon then leave it as it is, and preventing thermal diffusion while in bed to sleep warmly and comfortably.

A polyvinyl chloride pipe 2, which is wound around with a string 3, and the same pipe, which is not wound, are alternately put into the groove on the side board 1 to form a floor board. Then, the bed is assembled with a fed board 4 and a foot board 5.