Disclosed is a method of producing a polyethylene terephthalate-based polyester fiber, including spinning polyethylene terephthalate based polyester to produce an undrawn yarn with an intrinsic viscosity of 0.83 or more and a density of 1.338 g/cm3 or more, multi-stage drawing the undrawn yarn, heat-setting the drawn yarn, relaxing the heat-set yarn, and winding the relaxed yarn to produce the resulting drawn yarn with an intrinsic viscosity of 0.83 or more and a density of 1.38 to 1.3865 g/cm3. Compared to a prior polyester yarn with high modulus and low shrinkage, produced according to conventional melt-spinning and drawing processes, an industrial polyester yarn with high modulus and low shrinkage according to the present invention contributes to significantly improving strength retention (tenacity of a dip cord/tenacity of a grey yarn) of the dip cord, produced by treating the polyester yarn of the present invention with an adhesive (RFL) and subsequently heat-treating the RFL-treated polyester yarn. Therefore, the polyester multifilament yarn according to the present invention is useful as a tire cord.