To provide link mechanism that can easily constitute a structure with a large curvature while being excellent in strength and simple in structure.

Two parallel members 11, 12 and two non-parallel members 13, 14 are connected in quadrangular shape through hinges 17a, 17c, 17d, 17f. The opposed parallel members 11, 12 are connected by a connecting member 15 parallel to one non-parallel member 13 through hinges 17b, 17e. The diagonal hinges 17a, 17f are connected by an expandable diagonal member 16, and a space between the hinges 17c, 17f of the other non-parallel member 14 is made changeable.