In this paper, the novel bearing tester was developed by new method using a wire tension to obtain the coefficient of friction (COF) of micro bearings. Because the conventional bearing testers mostly use bulky and friction-nature torque sensors, there is a limitation to measure the minute rotational torques of the micro bearings. In order to overcome the previous limitation and estimate the COFs of very small journal bearings (inner diameter < 10 mm), the bearing was placed freely along the x-axis and the tension of the wire which wrapped the bearing and was connected between the counterweight and the load cell was measured. The COFs were calculated by dividing the radial friction force obtained by the wire tension by the initial vertical load given by the mass of the counterweight and the bearing module. The developed bearing tester could measure the COFs of the micro journal bearing of various shape and size effectively. The validity of the bearing tester was verified by several friction measuring tests. The system also showed very high repeatability and precision.