PURPOSE: To obtain the subject yarn composed of an interlocked yarn consisting of multiple filaments containing far infrared-radiating ceramic fine powder, having specific structure and state and exhibiting excellent heat-insulation, spun yarn-like feeling and appearance and excellent knitting and weaving suitability.

CONSTITUTION: The objective yarn is an interlocked yarn composed of multiple filaments containing 0.1-20wt.% of far infrared-radiating ceramic fine powder and accounting for ≥20wt.% of the yarn. The loop index having a distance of ≤0.5mm from the yarn surface is ≥60/m and the loop index of ≥1.5mm is <10/m. The yarn can be produced e.g., by aligning multiple filaments containing ceramic fine powder such as zirconium carbide powder parallel to the other multiple filaments and applying fluid-turbulent treatment to the filaments under over-feeding condition, thereby forming interlocks between the filaments and forming loop fluffs.