In this paper, we report a simple, effective method for the visualization of a cell–attached nanointerface using localized surface plasmon resonance (LSPR) excited on a self–assembled metal nanoparticle sheet. The LSPR on the nanoparticle sheet provides high–contrast interfacial images due to the confined light at the nanointerface. The experiment of immobilized RBL–2H3 cells with fluorescence–labeled actin filaments revealed high axial resolution for the focal adhesion even under a regular epifluorescence microscope. This imaging technique can be applied even for live–cell imaging under a total internal reflection fluorescence (TIRF) microscope. This non–scanning–type, high–resolution imaging method will be an effective tool for monitoring interfacial phenomena including molecular level of rapid reaction or various cellular and molecular dynamics.