A gas generator 1 for an air belt apparatus which is used in an air belt apparatus for inflating an air belt by introducing a gas discharged from the gas generator, includes a solid gas generating agent adapted to be burnt and generate at least one of a gas and a heat, and a housing accommodating the solid gas generating agent. The housing is provided with a gas discharging port 2 for discharging a gas generated inside the housing in the radial direction of the housing.