PROBLEM TO BE SOLVED: To provide a synthesis method that makes it possible to produce high-purity glycyrrhizinic acid or galacturo glycyrrhizinic acid, simply and in high yields.SOLUTION: A production method includes performing glycosylation of position-3 hydroxy group of glycyrrhetinic acid, then performing selective galactosylation or glycosylation at position-2, and through deprotection, performing selective oxidation of a primary hydroxy group.SELECTED DRAWING: None【課題】高純度のグリチルリチン酸またはガラクツログリチルリチン酸を簡便かつ高収率で製造することが可能な合成方法を提供すること。【解決手段】グリチルレチン酸の3位水酸基をグリコシル化し、次いで2’位に選択的なガラクトシル化またはグリコシル化を行い、脱保護を経て、一級水酸基の選択的酸化を行うことを特徴とする製造方法。【選択図】なし