To enable to expand and fold a leg without labor.

This leg is provided with a base part 2 fixed to the under surface of a pedestal 40, a leg part 13 in which wheels 16, 16 are fixed to a lower axle 17 of parallel leg plates 14, 14, a release link part 8 with a flat- shaped base plate, a parallel first link part 21 and a parallel second link part 27. A shaft 12 is the axis core for the release link part 8 and the leg part 13, a slide shaft 26 is the axis core of the first link part 21, a shaft 33 is the axis core of the second link part 27, a shaft 32 is the axis core of the first link part 21 and the second link part 27, and all of these can be rotated. A pair of elastic members 34, 34 are provided between both ends of the slide shaft 26 and the shaft 33, and the leg part 13 can be expanded and folded by the rising and lowering operations of the pedestal 40.