The napuliar stages of Harpaciticus nipponicus Ito reared in the laboratory are descirbed and illustrated in detail. Ovigerous females of h. nipponicus were collected from the intertidal zone of Kuryongpo Yougil-gun Kyongangbuk-do. Korea. This species passed through 6 naupilar stages before metamorphosis to the first copepodid stage. At $20^{circ}C$, the first copepo양 stage was attained in 6-8 (mean 7 ) days after hatching. The nauplii of Harpacticus species can be distinguished from those of other Harpacticid genera by the maxillule, pereiopods, and caudal setae. The nauplii of h. nipponicus are similiar in morphology to those of H. uniremis but distinguished by the differences in naupliar size and appendage setation. A key to identify the naupliar stages of this speices is briefly discussed.