The present invention relates to a gas combustor, which includes a casing unit of the gas combustor and a detachable ignition module, the detachable ignition module is to have an igniter being modularized as a single unit, thereby being enabled to be inserted in or removed from an insertion slot preformed on a surface of the casing unit of the gas combustor, and a cathode connecting joint and a anode connecting joint of the detachable ignition module are respectively in contact with or separated from an electric conductive wire installed in the insertion slot, thereby establishing or terminating an electric connection, so the inconvenience and possible danger of replacing the igniter by the user himself is avoided.