Electrostatic inkjet phenomena took place when high voltage was applied between an insulative capillary tube filled with ion conductive liquid and a metal plate electrode. An investigation has been carried out on the control of a micro droplet by the electrostatic inkjet phenomena, because the electrostatic inkjet phenomena has a merit that the diameter of the droplet can be controlled by the application of the electric field and it is possible to treat highly viscous liquid. It was observed that a Taylor cone of the liquid was formed at an end of a tube and the tip of the cone was broken to form a very small droplet at the beginning of the corona discharge. First technique was 3D printing utilizing highly viscous paste. The formation of the droplet was controlled by the application of pulse voltage. Box and pyramid structure were printed. The aspect ratio was over 10. Second technique was thinning a metal rod utilizing etching liquid. A metal rod was set on the metal plate electrode. The diameter of the rod was controlled by the time of voltage application. The last technique was creating a hole on a shin metal sheet utilizing etching liquid. A shin metal sheet was set on the metal plate electrode. Hole diameter, less than 10 um to some 100 um was controlled by the amplitude of the applied voltage.