New fabrication process for the nano-meter order structure was developed using the STM. The process named "STM nano-oxidation process" could oxidize the titanium metal to form the few tens of nano-meter oxidized titanium line which works as an energy barrier for the electron. The electrical properties of the TiOx line are examined in detail. The single electron transistors with back gate, or side gate, and also those with multi-islands are fabricated using STM nano-oxidation process. The single electron transistor showed the clear Coulomb gap of -160 mV, and the Coulomb oscillation with 400 mV period even at room temperature.