A method of treating or preventing multiple sclerosis includes administering a therapeutically effective amount of a cyclohexane derivative represented by Formula (I):wherein A is a substituent represented by Formula (IIa) or (IIb):R1 and R2 are each independently a hydrogen atom, chlorine atom, C1-C3 haloalkyl, C1-C4 alkyl, C1-C4 alkoxy, or cyano； R3 is a hydrogen atom or chlorine atom； R4 is a fluorine atom, hydroxymethyl, or hydroxyl； R5 and R6 are each independently a hydrogen atom, fluorine atom, C1-C3 haloalkyl, carboxyl, methoxycarbonyl, ethoxycarbonyl, C1-C4 alkoxy, hydroxyl, or C2-C5 alkylcarbonyloxy, or optionally together form oxo； R7 and R8 are each independently a hydrogen atom or fluorine atom； Y is an oxygen atom or sulfur atom； and Z is a nitrogen atom or methine or a pharmaceutically acceptable salt thereof to a mammal.
