4-(tert-Octyl)phenol derivatives bearing the D-mannitol substructure (6a, 6b, 7) were prepared from $small{D}$-mannitol and evaluated their anticancer activity against human lung (A549) and prostate (Lncap, Du145, PC3) cancer cell lines. Among derivatives tested, the bis(tert-octyl)phenoxy compound 7 exhibited strongest proliferation inhibitory activities against human cancer cell lines tested, especially high sensitivity to human Du145 prostate cancer cells ($IC_{50}=7.3{mu}M$).