A gas generator, comprising: a housing including a first shell having a top plate and a circumferential wall portion and a second shell having a bottom plate and a circumferential wall portion; a gas discharge port formed in the top plate or the circumferential wall portion of the first shell; an inner cylindrical member disposed inside the housing, and defining an ignition chamber therein and a combustion chamber in an outside thereof; an ignition device disposed inside the ignition chamber; and a solid gas generating agent charged in the combustion chamber to generate combustion gas, the inner cylindrical member including an opening at one end, which is closed, an opening at the other end, which is closed by the ignition device attached thereto, a plurality of nozzles provided in a circumferential wall of the inner cylindrical member to communicate the ignition chamber with the combustion chamber; the combustion chamber including a radially inside portion defined by the circumferential wall of the inner cylindrical member and a radially outside portion defined by at least the circumferential wall portion of the second shell, and characterized in that the inner cylindrical member further includes a guide member (35; 36; 37) provided at least in an outer side or an inner side of the circumferential wall, so that combustion products generated inside the ignition chamber are discharged from the nozzles and guided-towards the bottom plate of the second shell; when the guide member (35; 37) is formed in the outer side of the circumferential wall of the inner cylindrical member, an opening defined by the circumferential wall of the inner cylindrical member and a distal portion of the guide member (35; 37) serves as an outlet (35a; 38) for combustion products discharged from the inner cylindrical member during actuation; when the guide member is formed in the inner side of the inner cylindrical member, the nozzles serve as the outlet for the combustion products discharged from the inner cylindrical member during actuation; and the outlet (35a; 38) is formed closer to the bottom plate than to the gas discharge port. a housing including a first shell having a top plate and a circumferential wall portion and a second shell having a bottom plate and a circumferential wall portion; a gas discharge port formed in the top plate or the circumferential wall portion of the first shell; an inner cylindrical member disposed inside the housing, and defining an ignition chamber therein and a combustion chamber in an outside thereof; an ignition device disposed inside the ignition chamber; and a solid gas generating agent charged in the combustion chamber to generate combustion gas, the inner cylindrical member including an opening at one end, which is closed, an opening at the other end, which is closed by the ignition device attached thereto, a plurality of nozzles provided in a circumferential wall of the inner cylindrical member to communicate the ignition chamber with the combustion chamber; the combustion chamber including a radially inside portion defined by the circumferential wall of the inner cylindrical member and a radially outside portion defined by at least the circumferential wall portion of the second shell, and characterized in that the inner cylindrical member further includes a guide member (35; 36; 37) provided at least in an outer side or an inner side of the circumferential wall, so that combustion products generated inside the ignition chamber are discharged from the nozzles and guided-towards the bottom plate of the second shell; when the guide member (35; 37) is formed in the outer side of the circumferential wall of the inner cylindrical member, an opening defined by the circumferential wall of the inner cylindrical member and a distal portion of the guide member (35; 37) serves as an outlet (35a; 38) for combustion products discharged from the inner cylindrical member during actuation; when the guide member is formed in the inner side of the inner cylindrical member, the nozzles serve as the outlet for the combustion products discharged from the inner cylindrical member during actuation; and the outlet (35a; 38) is formed closer to the bottom plate than to the gas discharge port.