Patented is a conjugated fiber comprising a crystalline aliphatic polyester having a melting point of not less than 140°C. The fiber has a composition comprising an aliphatic polyester and 1-50% by weight of one compound selected from the group consisting of a polyether having a C2 to C4 alkylene group, their derivatives, an organic compound having a sulfo group, an organic compound having a sulfate group, an organic compound having a carboxyl group, an organic compound having a phosphate group, an organic compound having an amino group, an organic compound having an amido group and an organic compound having an amino group and an amido group. The polyester and the composition are conjugated in a single filament and, in the cross section, the composition divides the polyester into at least two portions.