This paper presents a sampled-data design approach for decoherence control of a single qubit with operator errors. The required control performance is defined using a sliding mode domain and the control law is designed offline and then utilized online with a single qubit subject to decoherence with operator errors. Three cases are analyzed in detail including approximate amplitude damping decoherence, approximate phase damping decoherence and approximate depolarizing decoherence. Sampling periods are specifically designed for these cases to guarantee the required control performance.