Switched Reluctance (SR) motor attracts attention as motor that use no rare earth materials. And it is a candidate technology for electric vehicle application. In addition, Axial-gap structure has possibility of effective utilization of In-Wheel flat motor space. However, it is not established how to decide optimum design of Axial-gap SR motor. This paper mainly discusses the optimum design to maximize the torque-volume density of Axial-gap SR motor focused on the stator pole length. First, optimum stator pole length for increase torque-volume density is examined using FEA. The magnetomotive force is increasing when stator pole length is increasing, but motor total volume is also increasing. So, the optimum stator pole length regarding to the diameter for maximum torque-volume density is found. After that, a new Axial-gap SR motor is designed. Finally, the designed Axial-gap SR motor has high torque density as 51N·m/l.