In this paper, an indirect adaptive fuzzy controller is introduced for controlling a nonlinear rotational inverted pendulum with time-varying parameters. In fact, choosing this type of controller is regarded as a wise choice since this particular system performance is highly sensitive to unavoidable unknown model changes. Hence, a conventional controller is firstly designed through feedback linearization method, and applied to the system. Feedback linearization method here is used for two purposes; to attain an approximation of necessary system dynamics and to assess the performance of the proposed adaptive fuzzy controller by comparing the results of both adaptive fuzzy and feedback linearization controllers. An indirect adaptive fuzzy controller, resistant to parameter variations is then proposed. The general structure of the adaptive controller is specified in the first stage. In the second stage, its parameters are regulated with the aid of two fuzzy systems. Parameters are regulated based on the Lyapunov stability theorem such that the closed loop system is stabilized and zero tracking error is attained. Finally, the results of the proposed and the conventional approaches are compared. Results proved that the adaptive fuzzy controller performed much more efficiently than the classical controller, especially against parameters variations.