To restrain influence of heat by lowering the temperature of gas, while exhibiting the function of distributing the gas jetted from a gas jetting part of an inflator.

The gas distribution structure distributes the gas G jetted from the gas jetting part 24 of the inflator 21 to two inflating parts of an airbag by pointing in the direction along the axis L by an inner tube 40. A pair of folding pieces 46 are formed as the inner tube 40 by bending a long size fabric web along a folding line 45, and both folding pieces 46 are mutually joined by a pair of joining parts 53 and 55 orthogonal to the folding line 45, to form an object of opening an edge part 57 opposed to the folding line 45. The inflator 21 is inserted into the inner tube 40 so that the gas jetting part 24 is positioned in a place deviated to the second joining part 55 side and the folding line 45 side of the inner tube 40, and a gas discharge hole 59 is arranged in a place near the first joining part 53 on the folding line 45.