Polymer melt/solid interfaces have been previously investigated by surface force apparatus (SFA) , X-ray reflectivity (XRR) , and static-mode atomic force microscopy (AFM) . They have revealed that the layered density distribution exists temporarily at the interface and disappears with relaxation over time. However, SFA and XRR lack in-plane resolution and only provide the structural information averaged in a plane parallel to the solid surfaces. Since polymers have long molecular chains (10-100 nm) and each molecule has a structural degree of freedom, the averaged one-dimensional information is insufficient to analyze these interfaces' spatial structures. Also, XRR detects only periodic density distribution on the interface and does not provide information on mechanical properties. SFA and AFM are effective for mechanical property analysis because of their principle of detecting forces. However, static-mode AFM cannot individually detect the conservative and dissipative components of the mechanical response, which corresponds to elasticity and viscosity. Since polymer melts have viscoelasticity, unlike low molecular weight liquids, it is essential to detect their viscosity and elasticity separately. Also, while static-mode AFM has a nanometer-scale in-plane spatial resolution, the previous studies are mostly limited to one-dimensional force-distance curve measurements just across under the tip, which cannot visualize the in-plane distribution of the mechanical properties based on liquid molecules. Therefore, a method capable of mapping interfacial structure and mechanical properties with high spatial resolution is needed. Dynamic mode AFM, especially frequency modulation (FM-) AFM , would be a more powerful technique to detect conservative and dissipative interactions separately because it detects the interaction force as a change of resonance properties of the force sensor. FM-AFM has widely been applied for high-resolution structural analysis on solid/liquid interfaces. In general, FM-AFM analysis in highly viscous liquids is difficult because the viscosity of the liquid depresses the resonant quality factor of sensors and the force sensitivity, and most FM-AFM studies are limited to low-molecular-weight liquids . To overcome this issue, we have developed FM-AFM utilizing a quartz tuning fork sensor (qPlus sensor ), which shows a higher quality factor than the conventional cantilevers even in a viscous liquid, and have achieved FM-AFM analysis of the interface between silicone oil (poly(dimethylsiloxane); PDMS) with a viscosity of 970 mPa•s (number-average molecular weight Mn ~ 26000 from calculation ) and mica. We successfully imaged the atomic-scale topography of the solid surface and the layered density distribution on the interface, representing the molecules-layering structures in which the PDMS molecular chains are oriented parallel to the mica surface. With these backgrounds, the nanoscopic structures and mechanical properties of polymer melt/solid interface were analyzed by FM-AFM with high spatial resolution using the qPlus sensor in this study. PDMS with a 9750 mPa•s viscosity was employed as the model polymer, whose molecular weight (Mn ~ 59000) is far above Mc. Furthermore, we studied the time-temperature dependence of these relaxation processes. In general, the temperature dependence of relaxation processes is determined by the activation energy , which depends on its relaxation mechanism.