Abstract: A gas generator includes an elongated cylindrical housing main body and a plug which closes an axial end portion of the housing main body. The plug made of a metal includes a substantially columnar body portion, a first flange portion located on a side of a first end surface, and a second flange portion located on a side of a second end surface. An annular groove portion defined by the body portion, the first flange portion, and the second flange portion is located in a circumferential surface of the plug. A metal flow in a portion which appears in a surface layer of the circumferential surface of the plug including a surface of the annular groove portion continuously extends to reach the second end surface from the first end surface along the circumferential surface without discontinuity in the circumferential surface.

Abstract: A gas generator includes an elongated cylindrical housing, an accommodation chamber defining member arranged in the housing, a gas generating agent, and an autoignition agent. The accommodation chamber defining member includes a cylindrical portion which extends in a direction in parallel to an axial direction of the housing and accommodates the gas generating agent therein. A heat insulating layer is located between the housing and the cylindrical portion. The autoignition agent is arranged in a portion inside the housing in the axial direction of the housing where no heat insulating layer is provided, as being in contact with the housing with a member made of a metal being interposed.

Abstract: A gas generator includes an elongated cylindrical housing, an accommodation chamber defining member arranged in the housing, a gas generating agent, and an autoignition agent. The accommodation chamber defining member includes a cylindrical portion which extends in a direction in parallel to an axial direction of the housing and accommodates the gas generating agent therein. A heat insulating layer is located between the housing and the cylindrical portion. The autoignition agent is arranged in a portion inside the housing in the axial direction of the housing where no heat insulating layer is provided, as being in contact with the housing with a member made of a metal being interposed.