The first asymmetric epoxidation of a tertiary allylic alcohol by the Katsuki-Sharpless reaction has been demonstrated using (E)-2,5-dihydroxy-2,5-dimethyl-3-hexene as a tertiary allylic alcohol substrate to afford optically active 3,4-epoxy-2,5-dihydroxy-2,5-dimethylhexane in 70% ee in an excellent chemical yield.