A toric air bag for a safety tire capable of sufficiently and equally contacting with a full inner face of a tire in the expansion-deformation of the toric air bag by a drop of an internal pressure in the tire, wherein at least an expansion-deforming portion of the toric air bag having a hollow torus shape as a whole is constructed with a tension support member, and to the expansion-deforming portion is given a property indicating a characteristic of extension ratio-tensile force that tensile force per unit width is substantially and gradually increased with the increase of elongation through the expansion-deformation.