The clustering of hydrogen-bonding molecules in liquid is ubiquitous and closely related to the various properties of the liquid. At the solid–liquid interface, the influence of solid surfaces on the interfacial structure of hydrogen-bonding clusters, which has remained underexplored, is key to controlling the interfacial properties of the liquids. In this study, we performed MD simulations to reveal the interfacial structures of ethanol clusters present on hydrophobic solid surfaces. The number density profile of the hydroxyl groups indicated the presence of a layered structure, and the orientation of the hydrogen bonds (HBs) differed between the layers. The ethanol molecules preferred the lateral HBs in the layers enriched with hydroxyl groups, whereas the perpendicular HBs were dominant in the interlayer regions with fewer hydroxyl groups. Analysis of the aspect ratio of the clusters revealed that the hydrophobic surface induced the formation of longer interfacial ethanol clusters in the lateral direction, even when the hydroxyl groups of the ethanol molecules were oriented perpendicular to the surface. The lateral HBs in the enriched regions connected with each other, whereas the perpendicular ones in the interlayer regions did not, resulting in the lateral clustering of the ethanol molecules.