To obtain a polyester-based multifilament yarn used for a warp yarn of a weaving capable of suppressing the increase of the number of a loom stopping caused by the warp yarn and producing the woven fabric at a high efficiency in a high speed weaving of' the polyester based multifilament yarn used for the warp yarn of a on twisted woven fabric without a sizing by a water jet loom, and provide a method for producing the same.

This polyester based multifilament yarn for weaving is a fluid interlacing treated polyester-based multifilament yarn and satisfies the following (A) to (D) simultaneously. (A) Elongation at break (EL) : 45%≤EL≤55%, (B) Degree of interlace (IL): 20/m≤IL≤50/m, (C) Remaining degree of interlace after abrasion at 50 g (II50): IL50≥10/m, (D) Mean length of interlace after abrasion at 50g (L50):I50≥5mm.