We collected stomach contents of sea kraits, Laticauda laticaudata, L. colubrina, and L. semifasciata around Ishigaki and Iriomote Islands of the southern Ryukyu Islands, Japan. Twelve species belonging to three families of Anguilliformes (Congridae, Muraenidae, and Ophichthidae) were detected as prey of fifteen individuals of L. laticaudata and seven individuals of L. colubrina. On the other hand, four species of the families Labridae, Opistognathidae, and Ptereleotridae were found in the stomach of three individuals of L. semifasciata. These results indicate that L. laticaudata and L. colubrina around the northern limit of their distribution (Ryukyu Islands, Japan) preyed upon anguilliform fish, as previously found at the southern limit of their distribution (Vanuatu and New Caledonia), whereas L. semifasciata consumed various families of fish other than Anguilliformes, as reported in Taiwan. Thus, it is confirmed that L. laticaudata and L. colubrina are specialist predators on anguilliform fish (eels) and that L. semifasciata is a generalist that consumes various fishes in tropical and subtropical coastal waters. The differences in prey species among these three sea kraits may not be due to geographical variation of prey availability.