This paper addresses the problem of linear adaptive controller for a class of un- certain continuous-time single-input single-output (SISO) nonaffine nonlinear dy- namic systems. Firstly, using the implicit function theory, the existence of an ideal controller which can achieve control objectives will be demonstrated. Nevertheless, this ideal controller can not be known and computed even if the system model is well known. The aim of our work is to construct this unknown ideal controller us- ing a simple linear controller with the gains updated online by a stable adaptation mechanism designed to minimize the error between the unknown ideal controller and the used linear controller. Since the mathematical model of the system is assumed unknown in this work, the proposed control scheme can be regarded as a simple model free controller for the studied nonaffine class of systems. We prove that the closed-loop system controlled is stable and all the signals are bounded. An application of the proposed linear adaptive controller for a nonaffine system is illustrated through the simulation results to demonstrate the effectiveness of the proposed control scheme.