By A. Peres and A. Stern's opinions a computational process evolves along a cyclic logic orbit defined by a computation. A. Stern thought that if we could design such a circuit, its operations can be extended to including nonconservative behavior associated with the external perturbations or internal quantum errors. A. Peres did not discuss how to make φM-1 ＝φo. A. Stern proposed only a necessary condition for a conservation of a state of a quantum circuit.In this paper we present a necessary and sufficient condition for a universal conservation of a state of a quantum circuit.We also find all operators which can allow the conservation.