Metal-based single electron transistors operating at liquid nitrogen temperature were fabricated. Multiple tunnel junctions with metal particles of about 3 nm in diameter were used to construct the transistors. In these transistors the gates are placed directly underneath the islands and separated only by a 10-nm-thick dielectric. The capacitance of the islands is less than 1 aF. Clear oscillations induced by gate bias voltage are observed in the current-voltage characteristics at 77 K.