PURPOSE: To obtain yarn having excellent bulkiness and bundling properties and high softness by making yarn complex by false twisting processing and fluid treatment.

CONSTITUTION: In winding thermoplastic yarn B on false twisted thermoplastic yarn A between a false twisting heater and a spindle in a overfeeding ratio of the yarn B larger than the yarn A, complex false twisting is carried out under a condition simultaneously satisfying the following formulas [1] and [2] and then the yarn is subjected to fluid interlacing treatment to produce specific conjugate false twisted textured yarn: TA×(DA)1/7≥420... [1]. TA-TB≥50... [2]. TA is temperature (°C) of a winding point (P) where the yarn B is wound on the yarn A, DA is fineness (denier) of the yarn A and TB is temperature (°C) at which thermal stress of the yarn B shows maximum.