We have been investigating fundamental characteristics of electrostatic inkjet and developing the inkjet for bio-technology and green-technology. It is not unusual that size is small and shape is complex in the field of these technologies. When the target is complex shape, robot arm printer is suitable to print because the gap between the printer and the target is easy to control. In this paper, we developed robot arm printer of electrostatic inkjet. Electrostatic inkjet module is set on commercial robot arm. Target is set on xy- linear stage. We can control the voltage application of electrostatic inkjet and motion of the robot arm and the xy- linear stage by PC. We investigate printing characteristics of the robot arm printer of electrostatic inkjet when the robot arm is running.