PROBLEM TO BE SOLVED: To provide an expansion and contraction structure including an elastic expansion/contraction member along an oblique direction in a product state and a fitting state, which is excellent in flexibility and is easily manufactured.SOLUTION: An expansion and contraction structure is provided in which a first sheet material 12S and a second sheet material 12H in the spread state are bonded by the adhesive agent 71 or the deposition processing intermittently arranged in an extension direction of an elastic expansion/contraction member and continuously extended in an oblique direction where an intersection angle &thetas on an acute angle side with respect to the extension direction of the elastic expansion/contraction member is more than 45 degrees to form a sheet joint part 70. The elastic expansion/contraction member is fixed to at least one of the first sheet material 12S and the second sheet material 12H at the position where the elastic expansion/contraction member crosses the sheet joint part 70. The first sheet material 12S and the second sheet material 12H are contracted along with contraction of the elastic expansion/contraction member so that portions positioned between the sheet joint parts 70 in the first sheet material 12S and the second sheet material 12H are expanded in mutually opposite directions to respectively form pleats 80.
