To provide a lightweight fluid mat or a fluid bed supporting a human body along its contour by providing a lightweight fluid, a bag body, and a fluid increasing means increasing the basic fluid distributed among fine granular bodies in the bag body.

A waterproof sheet 10 is formed with a nylon sheet 11 for keeping strength on the outside and a polyvinyl chloride sheet 12 having water permeability resistance on the inner side. A water absorbing body sheet 13 is laminated on the inner side of the polyvinyl chloride sheet 12, and the water absorbing body sheet 13 is kept in contact with a lightweight fluid 14 stored in the bag body 1. A fluid increasing function increasing the basic fluid distributed among fine granular bodies is provided in the stage of a sheet raw material used for a fluid mat or a fluid bed employing a fluid such as water. The lightweight fluid mat or fluid bed supporting a human body along its contour can be obtained.