PURPOSE: To give certainty to level adjustment and supporting and make a leg device mountable together with nice external appearance by mounting an outside landing body to a base body freely adjustable in a vertical direction, providing a connecting part to a support above the base body, and mounting an inside landing body freely adjustably in a vertical direction on an arm body part connected to the base body from the side opposite to a corner part.

CONSTITUTION: In the leg device of a structure, an upward recession 22 whose lower part is, at least, opened is formed at one corner part of a base body 21 rectangle-shaped in a top view, and an outside landing body 24 provided in this recession 22 is mounted to the base body 21 freely adjustably in a vertical direction. And, horizontal members 3 on the side of the structure are tailed into a pair of sides forming the corner part of the base body 21 to form downward stair parts 27 freely fixably, connecting parts 31 to the supports on the side of the structure are provided above the base body 21, an arm body part 34 is connected thereto from the side opposite to the corner part, and an inside landing body 38 is mounted on this arm body part 34 freely adjustably in a vertical direction.