Ig Mo Cho (益母草) has been used as remedy for invigorating blood circulation to remove blood stasis and relieving edema by inducing diuresis. With regard to the botanical origin of Ig Mo Cho, it has been considered to be Leonurus spiecies of Labiatae, but there has never been pharmacognostical confirmation on it. To clarify the botanical origin of Ig Mo Cho from Korea, the anatomical characteristics of Leonurus japonicus and L. sibiricus were studied. As a result, the botanical origin of Ig Mo Cho from Korea was proved the herba of Leonurus japonicus.