Five new species of phoxocephalid amphipods from sandy beaches in Korea belonging to two genera are described and figured: Mandibulophoxus mai n. sp., M. hongae n. sp., Grandifoxus malipoensis n. sp., G. cuspis n. sp., and G. bangpoensis n. sp. Keys to the known species and diagnoses of the genera are provided. The male characters of the genus Mandibulophoxus are given for the first time, but no male specimens of Grandifoxus were obtained during the present study.