Gas generator for air bag having any of the following members: deflecting member formed as tube portion capable of shielding gas discharge port formed on circumferential wall of housing from inside; coolant/filter means supporting member comprising annular portion arranged to face end surface of housing and wall portion contacting with inner periphery of coolant/filter means; coolant/filter means formed in cylindrical shape obtained by laminating wire mesh; housing securely fixing igniter included in ignition means, having opening portion for inserting and fixing igniter or igniter supporting member, wherein the opening portion is provided with connecting portion for fixing inserted igniter or igniter supporting member, and connecting portion is provided in inner side of housing rather than end surface having the opening portion.