The present invention provides a therapeutic or preventive agent for a disease caused by accumulation of an abnormal protein, including a compound represented by the following general formula (I): (wherein R1 and R2 each represent a hydrogen atom or a hydroxyl group ( However, one of R1 and R2 is a hydroxyl group)).以下の一般式（I）で表される化合物を含む、異常タンパク質の蓄積に起因する疾患の治療又は予防剤等を提供する：（式中、R1及びR2は、それぞれ水素原子又は水酸基を示す（但し、R1及びR2のいずれか一方は水酸基である））。
