PURPOSE: To ensure sufficient coupling strength by connecting corners between floor panels which are disposed in parallel to each other by means of a cross- shaped coulping device and a T-shaped one to form a raised floor for laying wiring cables or piping under the floor.

CONSTITUTION: A coupling groove 2 is formed in each corner of a floor panel 1 and a cross-shaped coupling device 4 and a T-shaped coupling device 7 are fitted into the grooves 2 to effect the connection between the floor panels 1. Next, the coupling device 4 has a cross-shape wherein four engaging plates 5 having the same shape protrude radially outwards and an engaging piece 6 is formed at the upper part of each of the plates 5. Further, the device 7 has a T-shape wherein an engaging piece protrudes from the central portion of an engaging plate 8 whose opposite edges extend laterally outwards. Consequently, detachment of floor panels can be easily carried out.