The edible purple laver, Porphyra yezoensis, contained 51.49±1.51 μg of vitamin B12 compounds per 100 g dry weight of the laver (mean±SEM, n=4). A vitamin B12 compound was purified from the lyophilized purple laver and partially characterized. The silica gel 60 TLC and reversed-phase HPLC patterns of the purified pink-colored compound were identical to those of authentic vitamin B12, but not to those of vitamin B12 analogues inactive for humans.