Ion cyclotron resonance heating is one of the plasma heating methods using the electromagnetic waves. An impedance matching device is installed near the LHD in order to transmit the power of the electromagnetic wave into the antenna in the LHD without loss and to protect the power amplifier from reflected wave. Since the impedance of the antenna (voltage/current) changes with time, the impedance matching device needs to be tuned automatically. In this theme, we will simulate the antenna impedance during plasma experiments and perform the automatic tuning test. We will also modify the tuning program if necessary.