This paper presents intelligent control of power assist system considering skill level of operators for wheelchair. In this paper, operability and anti-fluctuation running against the fluctuation of human force added to the handle by operator are progressed by the proposed auto-tuning system of power-assist controller. A method to estimate the operator's skill level and appropriately adjust the parameters of power-assist controller is presented by applying Fuzzy reasoning method. The effectiveness of the proposed method is demonstrated through experiments of OMW wheelchair.