Molecular dynamics simulations were performed to investigate the interfacial liquid structure at the solid interface of a ethanol-cyclohexane mixture, a typical system with microheterogeneity in the liquid bulk. The degree of microheterogeneity was decreased, not only when the solid surface was hydrophilic as previously reported, but also when it was hydrophobic. However, the microscopic mechanism was different. The hydrophobic surfaces restricted the molecular orientation of ethanol, and hence, sterically suppressed the clustering of ethanol molecules in the in-plane direction.