The circle formation control problem for mobile sensor networks with bounded position measurement errors is addressed in this paper, where the sensors are required to form a prescribed formation on a given circle. Only the upper bounds of the measurement errors are assumed to be known by the sensors a priori. An estimation algorithm is firstly proposed to estimate the position difference between the sensors and its neighbors. Then, a distributed circle formation control law is developed for each sensor by using the estimated position difference. It is shown that the effect of the measurement errors on the formation task can be reduced under the proposed formation control laws. Finally, a numerical example is provided to illustrate the effectiveness of the proposed control laws.