To provide a leg structure of ground surface laid matter without sinking into the ground face even the ground surface is soft and weak and to minimize the weight of the leg part, by fixing a dome outer shell at the lower end of the ground surface laid matter and filling foam plastic into the outer shell member.

A leg part 1 of this leg structure of a ground surface laid matter comprises a leg 11 made of shape steel, etc., and an outer shell member 12 in a dome shape fixed to the lower end of the leg 11 via a control mechanism 14, and the inside of the outer shell member 12 is filled with foam plastic. The outer shell member 12 is formed into a dome shape by pressing, etc., using a metallic material or synthetic resin material. The size of the outer shell member 12 is decided corresponding to properties of the ground. Foamed plastic 13 is to enlarge the ground contact area of the leg part 1, and the materials and the expansion ratio of the foamed plastic are set so as the foamed plastic 13 to support the weight of the ground surface laid matter in cooperation with the outer shell member 12.