A backstepping-based adaptive control is designed for a class of one degree of freedom hysteretic system. The true hysteretic behavior does not need to be known for the controller design. A polynomial description is assumed with uncertain coefficients and an uncertain residual function. These uncertainties are bounded and lump the discrepancies between the adopted description and the real hysteretic behavior. The adaptive controller is able to handle these uncertainties and make the closed loop globally uniformly ultimately bounded when the system is subject to an unknown excitation from which a bound is known. The efficiency of the approach is tested by numerical simulations on a hysteretic system under a seismic excitation. This system is mathematically described by the differential Bouc-Wen model, which is widely used in structural dynamics.