PURPOSE: To provide a hollow polyester filament yarn having a tensile strength and tensile elongation higher than respective specific levels, containing a hollow part continuing in the fiber direction on single filament cross-section at a specific hollowness, giving a knot part having improved tightness and strength and suitable for knot fishing net.

CONSTITUTION: The objective hollow polyester yarn for knot fishing net is a multifilament yarn composed of filaments having a single filament fineness of preferably 10-80de and has the following characteristics. The hollow yarn has a tensile strength of ≥6.0g/de and a tensile elongation of preferably 20-30%. Furthermore, the hollow yarn contains a hollow part continuing in the direction of fiber axis on single filament cross-section at a hollowness of 5-20%. The poor tightness of knot and remarkable lowering of strength of the knot caused by the use of conventional polyester yarn for fishing net to a knot fishing net can be improved by the use of the present hollow polyester yarn for knot fishing net.