The present invention provides a sterol derivative or a pharmaceutically acceptable salt thereof having an activity to promote proliferation of neural stem cells. Namely, the present invention provides a sterol derivative represented by the general formula (I) (wherein Y represents optionally substituted lower alkyl or the like； Xa and Xb are the same or different, and represent a bond or the like； R1, R2, R3, R4, R7 and R8 are the same or different, and represent a hydrogen atom or the like； R5 and R6 are the same or different, and represent a hydrogen atom or the like； R9 represents a hydrogen atom or the like； R10 and R11 together represent a bond or the like； and R12 represents a hydrogen atom or the like) or a pharmaceutically acceptable salt thereof.
