This paper deals with a new mobile micro-robot using centrifugal force. Many mobile micro-robots using PZT elements have been developed, though their PZT elements generally require some high voltage amplifiers with electric cable lines. Therefore, it is a little difficult for the mobile micro-robot to move about in long and thin pipes. My proposed micro-robot consists of many brush fibers, two coreless motors and a button electric cell. These coreless motors with eccentric weights generate centrifugal forces which transmit to the brush fibers with elastictity, and consequently occur driving forces of the micro-robot. First, I derive a basic mathematical model of the mobile micro-robot using centrifugal forces. Next, some simple prototypes of this robot are developed, and the characteristics of high velocity is examined by experiment. Finally, I verify the validity of the proposed mathematical model by comparing simulation results with experimental results .