A sewing thread that is excellent in high-speed sewability and automatic sewing characteristics. In particular, a sewing thread comprising a plurality of under-twist yarns provided with upper twist, the yarns each consisting of a sheath-core structure yarn constituted of a multifilament of two or more filaments, wherein portion of the sheath-core structure yarn protrudes as loops on a yarn surface, the loops consisting of 50 to 300 loops of 0.7 to less than 1.2 mm length per m and 10 or less loops of 1.2 mm or more length per m, and wherein the yarns have a strength of 4 to 6 cN/dtex.