A new norditerpene alkaloid named 8-O-methylhypaconine (1) was isolated along with twelve known alkaloids from the underground parts of an unknown species of Aconitum plant cultivated in Korea. Among the known alkaloids, two dianthramide glucosides, N-(2′-β-glucopyranosyl-5′- hydroxysalicyl)-5-hydroxyanthranilic acid methyl ester (2) and N-(2′-β-glucopyranosyl-5′-hydroxysalicyl)-5-hydroxy-6- methoxyanthranilic acid methyl ester (3), were isolated from Aconitum plants for the first time. The structures were established on the basis of chemical and spectroscopic methods.