Present report deals with the essential oil components from Mentha japonica grown wild in Koitoikaigan, and M. arvensis type in Banseinuma, Harutoriko and Kussharoko, Hokkaido. The essential oil of M. entha japonica consisted mainly of limonene (0.7～1.2%), 3-octanone (0.4～0.5%), 3-octanol (0.4～0.5%), menthone (10.9～12.4%), isomenthone (0.5%), linalool (0.4%), menthyl acetate (0.5～0.7%), iso-isopulegone (0.4～0.5%), β-caryophyllene (1.2～2.6%), neomenthol (0.2～0.3%), thymol methyl ether (0.4～0.5%), menthol (5.6～7.4%), pulegone (60.2～66.7%). α-humulene (0.4～1.0), germacrene D (0.4～0.8%) and bicyclogermacrene (0.7～1.1%). The oil of M. arvensis type in Banseinuma was composed of limonene (4.3～11.1%), (Z)-β-ocimene (0.5～1.2%), (E)-β-ocimene (0.6～1.4%), 3-octyl acetate (0.6～0.8%), 3-octanol (0.6～0.8%), menthone (0.5%), (Z)-3-hexenyl 3-methyl butanoate (0.8～0.9%), linalool (49.3～62.3%), bornyl acetate (0.8%), β-caryophyllene (3.1～4.0%), menthol (0.0％), pulegone (0.5～0.8%), germacrene D (8.1～11.1%), bicyclogermacrene (0.8～1.0%), δ-cadinene (0.8～0.9%) and germacrene D-4-ol (1.1～1.2%). One of M. arvensis type in Harutoriko containing linalool (77.5%) as a main component in the oil, and menthone, menthol and pulegone were all of little content. Another one was constituted mainly of menthone (27.2～44.8%) and pulegone (19.7～29.9%), only linalool (1.8～7.4%). In addition, the oils of a M. arvensis in Kussharoko and its S1 plant were comprised of menthone (46.6, 10.0%), pulegone (38.4, 77.0%) and linalool (0.1, 0.1%). These M. arvensis type could run to seed whole of them
