To provide a floor structural body easily constructed as a floor structure body for a veranda or balcony of a house, excellent in drainage, design and a walkability and prevented from a slip and dislocation between a unit floor decorative member and a floor backing face.

Folded plate members 20 with valley parts and ridge parts are placed and fixed onto a frame to form a floor backing part C, and a plurality of floor decorative members are laid on the floor backing part C. Water flowing down from the floor decorative members is received by the valley parts of the folded plate members 20 and drained. The folded plate member 20 is a resin coated steel plate with the steel plate surface coated with resin, and unevenness is formed on the top face of each ridge part of the folded plate member 20.