Evaluation of $H_2$ / air fuel cell having an anion exchange membrane with the Cole-Cole plot method has been studied. $H_2$ was supplied to the anode at a constant flow rate and air was supplied to the cathode. The Cole-Cole plots have been measured while changing the air flow rate of the cathode. The obtained Cole-Cole plots have been evaluated by using the equivalent circuit of the fuel cell to get values of the membrane resistance and the reactive resistance. The experimental results show that the membrane value was slightly increased with increasing the air flow rate. On the other hand, the reactive resistance value decreased from 434 $m{Omega}/cm^2$ to 181 $m{Omega}/cm^2$. And the maximum power density was increased with decreasing the reactive resistance. They reveal that more influence on the performance of AEMFC is due to the reactive resistance. Decreasing the reactive resistance would improve the performance.