To provide unfolding support structure for supporting a hexahedron, in which the hexahedron is easily constituted.

The hexahedron is constituted by: a structure of arms 13, 23 having a folding point 3 between a joint 1 and a joint 2 and arms 14, 24 axisymmetric with the arms 13, 23 and having a folding point 6 between a joint 4 and a joint 5; and folding points 3, 6, 7, 8, 9, 10, 11, 12, 29, 30 as apexes formed by arranging four pairs of the structure between a joint base 7 and a joint base 8 at a right angle, and by shortening the distance between the joint bases 7, 8. The hexahedron is supported from the inside thereof by arms 15, 16, arms 17, 18, arms 19, 20, arms 21, 22, arms 25, 26, and arms 27, 28.