To provide a welded filament yarn for hair cloth having a flexural repulsive force extremely approximate to that of horse tail hair and suitable for forming an interlining cloth.

The welded filament yarn for hair cloth having a flexural repulsive force extremely approximate to that of horse tail hair and suitable for forming an interlining cloth is produced by using a sheath-core conjugate fiber having a sheath component composed of a copolymerized isophthalate copolyester having a melting point of 200-230C and a core component composed of a polyester homopolymer having a melting point of 250-260C at a core/sheath weight ratio of the fiber cross-section of 85:15 to 50:50, and welding the multifilament of the conjugate fiber to obtain the welded filament yarn having a thickness of 200-600 dtex and a flexural resilience of 1.0-2.0 cN.