To provide an expandable combined cell structure which can maintain and change the internal space of a cell.

The expandable combined cell structure, which forms a three-dimensional block, exhibits expansion over a wide range from the actual size to a neighborhood of zero with substantially producing no strain in planes of members, and can maintain and change the internal space of a cell by respectively forming the planes and edge lines of a combined polyhedral shape as rigid plane members and hinges, wherein the combined polyhedral shape is formed from a tiled array of two or more polyhedral shapes, the polyhedral shape is formed by joining virtual planar sheets, the sheet has a shape pattern inscribed on it, and the shape pattern is formed by repeating sequentially a fundamental area in which an isosceles trapezoid and parallelograms are arranged.