Four Japanese species of Plestiodon (Reptilia: Scincidae, formerly Eumeces): Plestiodon japonicus, Plestiodon finitimus, Plestiodon latiscutatus, and Plestiodon oshimensis oshimensis collected from Honshu, Shikoku, and Kyushu of the Japanese main islands and Amamioshima Island of the Ryukyus, Japan, were examined to make a more exact list of the parasitic nematodes and to reveal their distribution patterns. Six nematode species were found, including 2 species of Heterakidae (Meteterakis japonica and Meteterakis amamiensis), 1 species of Rhabdiasidae (Kurilonema markovi), 1 species of Trichostrongylidae (Oswaldocruzia socialis), 1 species of Cosmocercidae (Cosmocercidae gen. sp.), and 1 species of Pharyngodonidae (Pharyngodonidae gen. sp.). Six new hosts were recorded and 19 new localities were reported. Meteterakis amamiensis and K. markovi were distributed on both sides of Watase's line, which is known as a geographical distribution boundary between the Oriental and Palaearctic regions in Japan. A parapatric distribution of M. japonica and M. amamiensis in the Japanese main islands and coexistence of K. markovi and Neoentomelas asatoi in Amamioshima Island were revealed.