A gas generator comprises: a cylindrical housing (3) comprising an initiator shell (1) provided with a plurality of igniter devices (16, 17) and a closure shell (2); a combustion chamber formed in said housing (3) and loaded with gas generants (14a, 14b); a cylindrical member that partitions said combustion chamber into two or more combustion chambers (4, 7); and filter elements (6, 8) provided in the respective combustion chambers (4, 7) of the partitioned chamber wherein at least one of said filter elements (6, 8) is disk-shaped, and said respective combustion chambers (4, 7) are independent from each other.