To obtain a bulky combined yarn having thick and thin parts, having a soft and swollen touch and suitable for obtaining a fabric excellent in the changes of the appearance.

This bulky combined yarn comprises a blended and interlaced yarn alternately having thick parts A each comprising many sheath yarns (b) accumulated around a core yarn (a) and thin parts B comprising the core yarn (a) and the sheath yarn (b) which are mutually blended and interlaced. The core yarn (a) comprises multifilaments having a single filament fineness of ≤1 denier and a hot water shrinkage rate of ≤10%, and the sheath yarn (b) comprises highly shrinkable multifilaments having a hot water shrinkage rate of ≥20% and a thermal shrinkage stress of ≥0.4g/d. The treatment of the blended and interlaced yarn with hot water gives a form alternately having thick parts A comprising the sheath yarns (b) bundled around the core yarn (a) and thin parts B having the sheath yarn (b) in the core part in the longitudinal direction of the yarn.