The study deals with the development of an in-process and direct measuring method for the electrode motion generated by the automatic discharge gap controller. The controller is equipped with an electrode for electrical discharge machining and an actuator made of shape memory alloy, and can autonomously maintain a stable electrical discharge machining with its electrode positioned properly and continuously. However, the electrode motion cannot be directly measured due to a minute and high-speed motion in a working fluid during electrical discharge machining. This means that there is no way to optimize the controller and to even prove that the controller can move its electrode actually. Therefore, the authors have developed an in-process and direct measuring method of the electrode motion of the controller. From experimental results, it is found that the developed method has the ability to measure the electrode motion.