We are engaged in research about autonomous rice field operation. We have developed an automated tractor, a rice transplanter and a combine harvester. These automated agricultural machineries are guided by a global positioning system (GPS) and a direction sensor such as inertia measurement unit (IMU) using the controller area network (CAN) bus. Because each machine is used for a limited period of time in a year, we plan to share a main control computer and navigation sensors among automated machineries. We expect to deliver autonomous operation in paddy field at lower cost and to shorten the development period of each machine. The actuator control command and data communication protocols comply with the ISO 11783. In this paper, we report about project outline and explain about a rice transplanter as an example of automated agricultural machinery. © 2011 IEEE.