This study on the four families (Leucothoidae, Melitidae, Pleustidae, and Stenothoidae) of gammaridean and the one family (Caprellidae) of caprellidean amphipods of Ulreung Island was based on the materials collected at eight localities in Ulreung Island. Ten species of six genera were identified. Of these, he (Elasmopus korrunus, and Muero breuispina) are new to science. Four species (Leucothoe nogotoi, 1. spinicawa, Paropleustes denhouini, and Stenothoe volido) are new records for Korean craters. Five species were described and six Lvere illustrated.