To provide a unit skeletal structure of a construction, using a three-dimensional truss that is formed of single-shaped members and can secure a wide space therein.

In construction of the unit skeletal structure, four triangular trusses 2 are each obtained by annularly connecting three skeletal members A of the same length, together, and bottom sides 3 of the respective triangular trusses 2 are pin-connected together into a quadrangle 7, to thereby form a quadrangular pyramid developed truss 4. Then, four triangular vertexes 5a, 5b, 5c, 5d of each of a pair of the quadrangular pyramid developed trusses 4, 4 are abutted on the counterpart vertexes, and a unit U of a vector balancing body type truss 1 having the quadrangles 7 as a bottom surface and a top surface and a pair of four triangles 6 as side surfaces, is formed. Next, two of the units U thus formed are opposed to each other via any of the side surfaces, and mutually opposed four nodal points (8a and 8c, and 8b and 8d) of the bottom sides 3 and the top sides 3 of the respective opposed side surfaces are coupled with each other by extending joint members B having the same length as that of the skeletal member A. Further, abutted nodal points 9 of the pairing triangles 6 on the side surfaces opposed to each other are connected together, and the two units U are coupled with each other in a side surface direction, to thereby construct the stable three-dimensional truss structure.