Three new types of biflavone are reported: robustaflavone, 6-C-methylamentoflavone and ochnaflavone besides hitherto known four types, amentoflavone (1a), cupressuflavone (2a), agathisflavone (3a) and hinoki-flavone (4a). Robustaflavone was found in the leaves of Agathis robusta and the structure was established in a form of its hexamethyl ether (10), m.p. 305-308°.6-C-methyl-7-O-methylamentoflavone (13) was isolated from the leaves of Cephalotaxus harringtonia as the first example of C-methyl biflavones. Ochnaflavone (OSI, 15), and its mono- (OSII, 16) and di-(OSIII, 17) methyl ethers were isolated from the leaves of Ochna squarrosa (Ochnaceae) as three members of a new type biflavone which has a lingkage between side phenyls (Tab. 4). The structures of these new biflavones were easily elucidated mainly by using a shift reagent, Eu(FOD)_3 in the NMR spectra of their methyl ethers because H-6 showed much larger S-values than those of H-8 (Tab. 1 and 2). The synthesis of two compounds 14 and 20 starting from 18 and 19 respectively confirmed the structure 15 for ochnaflavone. It was also found that the shift reagent is similarly useful in the structure elucidation of isoflavone and xanthone derivatives.