PURPOSE: To manufacture the titled fiber having particular fine structure and excellent level-dyeing property, by melt-spinning nylon 66, steaming the fiber with a specific amount of steam using a steam-conditioning column having a specific length, winding at a low speed, and drawing the obtained fiber.

CONSTITUTION: Nylon 66 polymer is melted and extruded from the spinneret 1, and cooled with chilled air between the heat-insulation cylinder 2 and the inlet of the steam-conditioning column 4. Steam is applied to the fiber at a rate of ≤5g/min with the steam-conditioning column 4 having a length of ≤30cm, and wound with the winder 9 at a winding rate of ≤1,200m/min. The objective fiber manufactured by this process has a diffraction intensity ratio (R) of the reflection at 2θ=11° to that of (010)+(110) plane of ≥0.8, the apparent crystal size (ACS) obtained from the reflection of the (100) plane of ≥85%, and a crystal perfection index (CPI) of ≥55% measured by X-ray diffraction intensity measurement.