Characterization of the solid-liquid interfaces at the molecular level has recently become possible. This review summarizes our recent studies including new observations of liquid adsorption and a novel measurement for characterizing confined liquids. We have found that molecules with the hydrogen-bonding groups such as alcohol and acid form the molecular macroclusters when they are adsorbed on the silica surface in nonpolar solvents. This is caused by hydrogen-bonding between the surface silanol groups and adsorbed molecules as well as between these molecules. We also have developed a resonance shear measurement technique using the surface force apparatus which can control the thickness of the confined liquids at a resolution of 0.1 nm. These studies provide understandings of interfacial phenomena of the molecular level, which are not only important as foundations of interface science but useful for designing nano-and micro-devices and processes for manufacturing nano-materials.