PURPOSE: To improve the terrain error of a satellite in the order of one digit or less, by detecting the angular error of the communication antenna toward the objection of the earth, based on the electromagnetic waves received with the tracing antenna receiving the electromagnetic waves from the objective on the earth and by controlling so that the error is zeroed.

CONSTITUTION: In the stationary satellite 3 moving round the upper sky of the equator of the earth 1 providing the communication antenna 4, the tracing antenna which receives the electromagnetic waves fed from the ground station 2 on the earth 1 is provided. The electromagnetic waves received with this antenna 5 is added to the tracing receiver 7 and the output of the receiver 7 is fed to the control circuit 8. Further, the control circuit 8 processes for the operation for the output from the receiver 7 and controls the tracing drive mechanism 6 via the driving circuit 9, so that the tracing angular error can be zeroed. Further, the communication antenna 4 and the tracing antenna 5 are driven with the tracing drive mechanism 6 in common use, allowing to reduce the tracing angular error.