Helminth parasites collected at postmortem from the alimentary tracts of 5 Japanese giant salamanders, Andrias japonicus (Temminck, 1837), are reported. One trematode, Liolope copulans (Cohn, 1902); and 5 nematodes, Amphibiocapillaria tritonispunctati (Diesing, 1851), Dioctophyme renale (Goeze, 1782) (larva), Spiroxys hanzaki Hasegawa, Miyata et Doi, 1998, Kathlaniidae sp. (larva), and Physalopteroidea sp. (larva) were found. Examination of premolt and molting larvae of S. hanzaki showed that the advanced third-stage larvae molt directly to the adult stage. Strict host specificity of some helminths is surmised to be linked to the piscivorous nature of the giant salamander. This is the first report of A. tritonispunctati and D. renale from A. japonicus. The chromosome number of L. copulans is recorded for the first time.