PURPOSE: To obtain a processed yarn having silky wool feeling and excellent crispness, body and resiliency by using a drawn and crimped polyester copolymer yarn as the core yarn and a low-orientation crimped polyester yarn as the sheath yarn and winding the sheath yarn around the core yarn.

CONSTITUTION: A drawn polyester copolymer yarn 1 copolymerized with 5-18mol% of a copolymerizing component and a low-orientation polyester yarn 2 are crimped, e.g. by passing through a heater 5 and a false-twisting tool 6 to obtain the objective processed yarn 10 composed of the low-orientation crimped polyester yarn as the sheath yarn wound around a core yarn. The stretch recovery and the thermal shrinkage of the processed yarn are adjusted to 15-23% and ≥5%, respectively, by adjusting the thermal treatment conditions, etc.