A nano-satellite which mounts an attitude control system has little space. Therefore, there are few choices of attitude control methods. The vacuum arc thruster of this research is small and lightweight, thus it is suitable for the attitude control of the nano-satellite, while the possibility of the attitude control system of a nano satellite is extended. This research evaluates the performance of a vacuum arc thruster, a thrust density of which is very small. Therefore, the evaluating device should detect small thrust. This detection is performed from displacement of a thrust target. The performance of the vacuum arc thruster was evaluated by the impulse bit in this research. The impulse bit of this thruster was μNs order. We measured velocity of the fluid. Result of the experiment, flight velocity of the fluid was found to be 12km/s approximately. Moreover, we changed applied voltage and capacitance of the discharge indicating circuit, and we found that the impulse bit changes.