A spun yarn comprising poly(trimethylene terephthalate) staple fibers at a content of at least 15% by weight, the spun yarn having an elastic recovery percentage of elongation at 5% elongation (%) ≥ 0.1 X + 70 (wherein X represents the content of poly(trimethylene terephthalate) staple fibers in the spun yarn (wt%)). The spun yarn is excellent in knitting and weaving characteristics, stretchability and stretch-back property and in shape stability and durability when worn for a prolonged period of time.