In recent years, a large number of studies have focused on micro-robots. Moreover, yearly contests have been held in order to develop micro-robot technologies. As a result of these activities, various types of micro-robot have been proposed, including motor-type, piezoelectric-element-type, and electromagnet-type micro-robots. The present study considers a moving mechanism of and a control method for an electro-magnet-type micro-robot that can not only run in a straight line but can also turn using only one electromagnet by adjusting the directions of permanent magnets installed in the robot and the input voltage applied to the electromagnet. In the present paper, the straight running of the micro-robot is mathematically modeled, and the characteristics of the motion of the micro-robot running straight on a horizontal plane and on an inclined plane are investigated through a number of simulations experiments.