We fabricated a single-electron (SE) device using gold nanoparticles (Au NPs). Drain, source, and gate electrodes on a SiO $${_2}$$ /Si substrate were formed using electron beam lithography (EBL) and thermal evaporation of Au. Subsequently, solutions of 3-nm-diameter and 5-nm-diameter Au NPs were dropped on the device to make current paths through Au NPs among the electrodes. Measurements of the device exhibited negative differential resistance (NDR) in the current–voltage characteristics between the drain and source electrodes at room temperature (298 K). The NDR behavior was tuned by applying a gate voltage.