Abstract: The device of the invention comprises an adjuster 6 having a supporting end 6a in contact with a floor F to support a foldable table 1 in restrained condition, a caster 7 movable between a retracted position A where the supporting end 7a thereof at least contacts the floor F simultaneously with the supporting end 6a of the adjuster 6 and a projecting position B where the supporting end 7a projects toward the floor F beyond the supporting end 6a of the adjuster 6, and an urging mechanism 80 for urging the caster 7 toward the floor F with a force greater than the gravity acting on the foldable table 1 when the caster 7 is at or adjacent the projecting position and with a force smaller than the gravity acting on the foldable table 1 when the caster 7 is at or adjacent the retracted position.