PURPOSE: To obtain a middle wadding material of polyester having excellent workability during packing blowing, flexibility, bulkiness (and fire resistance) similar to those of down.

CONSTITUTION: This middle wadding material comprising fibers having latent crimping obtained by using latently crimping polyesters prepared by bonding two kinds of polyester having ≥0.05 difference in intrinsic viscosity is composed of a collected material which has crimped parts and not crimped parts, is a mixture of 80-20% stable fibers A having 4-20 (d) fineness and 20-80% stable fibers B having ≤3 (d) fineness wherein the crimped parts of both the stable fibers are gathered into spherical parts and the not crimped parts are protruded from the spherical parts. A fire-resisting middle wadding material of polyester is obtained by using polyesters composed of at least one copolymerized with a specific organic phosphorus compound.