About 23% of the energy density of the universe is considered to be in a form of non-baryonic dark matter. One of the strong candidates of dark matter is a hypothetical particle called the axion. In an axion dark matter search haloscope experiment, axions coherently scatter off the magnetic-field potential in a frequency-tunable resonant cavity. A dynamic frequency tuning in the resonant cavity is essential to effectively scan through the relevant axion mass range. In CAPP18T axion search experiment at CAPP/IBS in KAIST, we use a rotating tuning-rod system. We develop a frequency tuning system using a Proportional Integral Derivative control and precision stepping motor system. In this presentation we report details of the tuning mechanism and accuracy of the setup which are interpreted in the axion mass parameter space.