Polymer melts have many unique characteristics, such as viscoelasticity and entanglement, which are not observed in low-molecular-weight compounds. The properties of polymer melts vary greatly depending on the degree of polymerization in addition to their chemical species (polyethylene, polyacetylene, polysiloxane, etc.). Large-molecular-weight polymer melts generally show high viscosity and take a long time to relax their molecules' conformation and mechanical response. In particular, those above around the critical molecular weight (Mc) exhibit significant non-Newtonian properties owing to the molecular entanglement. Polymer melts are not only used as materials on their own but are often used in combination with other solid materials, such as for lubrication or fabrication of composite materials. In these applications, the interfaces between polymer melts and solids play crucial roles. Thus, molecular-scale analysis of both the structure and the mechanical properties of the interfaces with highly viscous polymer melts, especially above Mc, would be crucial.