To provide a composite yarn excellent in puffiness, stretchability, soft touch, resilient feeling and natural unevenness feeling, all of which are typical of high-grade wool, to provide a method for producing the composite yarn, and to provide a woven/knitted fabric using the composite yarn.

The composite yarn is such that at least two kinds of polyester multifilaments A and B are combined with each other and the following properties (1) and (2) are satisfied simultaneously: (1) 1.5U%(%)10, and (2)-5boiling water shrinkage difference(A-B)(%)5. In this composite yarn, the multifilamnets A are uneven conjugate multifilaments having the ability to express crimps, and the multifilaments B are uneven multifilaments.