DOUBLE FLOOR

PROBLEM TO BE SOLVED: To facilitate execution work by fitting a ring body to a fitting part of a receiving stand installed on a column body, placing a floorboard on the receiving stand by hooking a hooking piece of the floorboard on this ring body, and engaging an engaging part on the reverse of the floorboard with an engaging part of the receiving stand by using this hook as a guide. SOLUTION: A floorboard support tool 12 where a receiving stand 18 is installed on a column body 17 is fixed to a floor surface 13, and a ring body 19 is fitted to and placed on a fitting part 31. Next, a floorboard 11 is placed on the receiving stand 18 by hooking a hooking piece 15 on a ring body 19, and an engaging part of the floorboard 11 is engaged with an engaging part 30 by using this hook as a guide. In this way, after the floorboard 11 is wholly placed, the column body 17 is rotated, and a height of the receiving stand 18 is adjusted. Afterwards, a cap 20 is screwed in the tip of the column body 17, and execution work is completed. Therefore, since engagement of the engaging part on the reverse of the floorboard can be facilitated, workability can be improved.