This ultrafine polyamide fiber is a polyamide fiber having a single-filament fineness of 0.10-0.50 dtex, in which the average number of fluffs per 12,000 m of the length of the filaments is 1.0 or less. The melt-spinning method of the invention for producing the ultrafine polyamide fiber comprises: cooling melt-spun filaments discharged from a spinneret having orifices annularly disposed in the peripheral part of the spinneret, using a cooler (3) which is located under the center of the spinneret and which blows cooling air against the melt-spun filaments ejected from the orifices, from inside or outside the melt-spun filaments to cool the melt-spun filaments; oiling the filaments using an annular oiling device (4) that has a disk-shaped guide part which is located vertically under the cooler (3) and in which single filaments come into contact with the periphery of the disk and that has an annular slit for oil ejection which has been formed right over the guide part along the periphery of the guide; and then collecting the filaments and simultaneously performing second-stage oiling, by means of a collecting guide type oiling device (5).