A total of 11 specimens of a nereidid polychaete, which had been collected from the inner part ("Bay of Miya" is the old place name) of lse Bay in central Japan and preserved in the Natural History Museum Vienna, were taxonomically examined. They were all identified as the brackishwater nereidid, Hediste japonica (Izuka, 1908), which was previously known only from the Ariake Sea and Seto Inland Sea in western Japan and the western coast of Korea. The new information indicates that this species formerly had a wider distribution extending to at least lse Bay in central Japan, though all Japanese populations of this species seem to have been extirpated except for a population remaining in the Ariake Sea.