A Smith predictor has been known as an effective controller to overcome a dead time. If the plant, however, is unstable, the closed-loop system cannot be stabilized with a Smith predictor. In order to stabilize an unstable plant with time delay, we propose a predictive control which is composed of an observer, a predictor and a controller. We refer to the realization of the predictor, and indicate an available type of model for it. In addition, we suggest the possibility that predictive control with a stable approximate model may be applied to an astatic plant.