To provide an airtight duct structure of a hollow wall, which is fixed to a through-hole even if the thicknesses of an inner wall material and an outer wall material of the hollow wall are varied, and maintains the air-tightness of a hollow space.

In the airtight duct structure of the hollow wall, the through duct member including a tubular member 1 and an end pressing member 8 is attached to through-holes a, b provided in the inner wall material A and outer wall material B of the hollow wall. The tubular member 1 is formed into a bellows pipe-shape corrugated spirally or in parallel, and includes an expansion portion 4, a front flange 6 and a rear flange 5 at both sides thereof, and an insert guide portion 7 protruded from the inner periphery of the front flange 6. The end pressing member 8 includes an engagement portion 10 to be fitted to the tubular member 1, a cylindrical portion 9 formed longer than the total length of the thickness of the inner wall material or outer wall material and the thickness of the front flange or rear flange, and a pressing flange portion 12 formed on the cylindrical portion 9. The tubular member 1 is inserted to each through-hole while being deformed, a protruding portion of the insert guide portion 7 is cut, and the end pressing member 8 is inserted from the outside of the rear flange 5 and the insert guide portion 7.