To solve the problem of lack of labor and decrease of skilled workers for agriculture, we propose the method of creating work schedule for some agricultural mobile robots which perform their respective task simultaneously. In addition to this, a mobile robot which is able to be controlled by positions obtained from the image sensors and heading angles from a geomagnetic direction sensor (GDS) is developed. The positioning system for the mobile robot is based on the principle of triangulation. The subsystem is able to follow the movement of the robot and measure the angle to the robot by image analysis. The main system calculates the robot position using two angles from the subsystems, and sends it to the robot by a telecommunication system. Finally, assuming to make robots do the hay transportation on meadow, a control algorithm for the mobile robot system is developed, and a field test is conducted on a grass land to evaluate the developed robot system.