PROBLEM TO BE SOLVED: To provide a saponin compound analogous to QS-21 currently favored in anticancer and antiviral vaccines.SOLUTION: This invention relates to a compound represented by a formula X, where ^^^ is a single bond or a double bond; W is Me, -CHO or the like; V is hydrogen or the like; Y is CH2, -O- or the like; and Z is a specific carbohydrate domain.【課題】抗癌及び抗ウイルスワクチンにおいて現在好まれるQS-21の類似サポニン化合物の提供。【解決手段】式Xで表される化合物。は単結合または二重結合;WはMe、-CHO等;Vは水素等;YはCH2、-O-等;Zは特定の糖質ドメイン。【選択図】なし