Genetic relationships were estimated by RAPD analysis by using 10-mer random primers in individuals of Lilium japonicum Thunb., native to Shimane and other Prefectures. UPGMA clustering analysis indicated that individuals of L. japonicum from various collection sites in Shimane and Ehime Prefectures had no distinct differences from each other and that they belonged to the same cluster at 0.588 level of similarity coefficient. However, they were distinguishable from those native to Nara, Wakayama, and Shizuoka Prefs. Similarity coefficient between L. japonicum native to Shimane, Ehime, Nara, Wakayama Prefs., and that native to Shizuoka Pref. was 0.428, and that between L. japonicum native to the first four prefectures and L. rubellum Baker was 0.429 which suggests that L. rubellum was included in the variation of L. japonicum. Thus, this species displays a large variation depending on its native habitats. These results suggest that when creating new cultivars of L. japonicum in Shimane Pref., the native parents should be cross with L. japonicum from Shizuoka or Wakayama Pref. to instill possible hybrid vigor in the hybrids between genetically remote L. japonicum individuals determined by RAPD analysis.