PROBLEM TO BE SOLVED: To provide a new anti-hepatitis B virus (HBV) drug.SOLUTION: An anti-HBV drug comprises a compound represented by formula (I), its salt or solvate thereof (where Base is formula (a) or its analog).COPYRIGHT: (C)2015,JPO&INPIT【課題】新たな抗B型肝炎ウイルス(HBV)薬の提供。【解決手段】式(I)で示される化合物、その塩又はそれらの溶媒和物を含む抗HBV薬。(Baseは、式(a)もしくはその類似体)【選択図】なし