Airbag

An airbag that is mounted on a vehicle, the airbag comprising:

• a bag-shaped airbag main body that is inflated as a gas flows into the airbag main body;
• at least one tension member that is disposed inside the airbag main body and regulates an inflated shape of the airbag main body;
• and
• at least one vent hole that is provided in the airbag main body and through which the gas in the airbag main body is discharged,
• wherein in two-dimensional view when an inner side of the inflated and deployed airbag main body is viewed from a direction orthogonal to the vent hole via the vent hole, the tension member has an overlapping portion that is disposed at a position overlapping the vent hole, and in a case where a direction orthogonal to a length direction of the tension member is an orthogonal direction, a dimension of at least a part of the overlapping portion in the orthogonal direction is smaller than a gap of a portion of the vent hole, which corresponds to the overlapping portion, in the orthogonal direction,
• wherein the overlapping portion is included in a narrow portion that has a dimension in the orthogonal direction smaller than other portions in the tension member, and
• the tension member is formed by a belt-shaped member having flexibility, and
• the narrow portion is formed such that a part of the belt-shaped member is folded in a width direction of the belt-shaped member and both end portions of the belt-shaped member in the width direction are overlapped with and fixed to each other at a folded portion.