In this paper, the driving mechanism and control strategy of a power assisting system for the walking chair have been proposed. This power assisting system must utilize the human power and realize the walking velocity that the human wants. Through experiments about a prototype of the walking chair, the characteristics of driving torque have been clarified. In order to grasp the condition to drive the crank by human that human can generate the maximum power without much fatigue, the relationship among the load torque, angular velocity and fatigue have been investigated. The characteristics of detection characteristics of human to the fluctuation of the torque and angular velocity have been also investigated. According to these experimental results, the experimental apparatus of power assisting system has been constructed and the control strategy and determination method of the parameter of control system have been proposed. Effectiveness of the proposed control strategy of the power assisting system has been confirmed through experiments.