Investigations were made on the behavior of various solvents to vitamin B_<12> and its dicyanide. The results of the experiments using crystalline vitamin B_<12> indicated that some of lower fatty acids such as n-, iso-valeric acids and n-caproic acid were as effective for extracting vitamin B_<12> as well known phenol or cresol. Vitamin B_<12> extracted with a fatty acid could be transferred to water from the organic phase by simultaneous addition of ether, butyl acetate, ethyl acetate or CaCO_3 with water. Further experiments using aqueous extracts of vitamin B_<12> from natural sources indicated that the solvent extraction procedure using iso-valeric acid followed by butyl acetate was no less effective for purifying B_<12> than that of plenol n-butanol followed by ether reported. Some of these fatty acids seemed to be promising solvents for extracting vitamin B_<12> from viewpoints of the strong affinity and selectivity for vitamin B_<12>, easiness of their recovery and so on.