PROBLEM TO BE SOLVED: To provide an immunostimulating agent superior in an immunostimulatory effect, particularly a compound useful as a vaccine adjuvant, a pharmaceutical composition containing the compound, a vaccine containing the compound and an antigen.SOLUTION: An immunostimulating agent contains at least one compound represented by the general formula (I) in the figure or a salt thereof. [In the formula, each symbol is as defined in the present specification.]SELECTED DRAWING: None【課題】免疫賦活作用に優れた免疫賦活剤、特にワクチンアジュバントとして有用な化合物、当該化合物を含む医薬組成物、当該化合物と抗原を含むワクチンの提供。【解決手段】一般式（Ｉ）：〔式中、各記号は、本明細書で定義した通りである。〕で表される化合物又はその塩の少なくとも１種を含む、免疫賦活剤。【選択図】なし
