PURPOSE: To reduce weight and electric power consumption while realizing highly accurate unloading operation.

CONSTITUTION: First and second magnetic torquers 16a and 16b are arranged almost in parallel with a roller shaft and a pitch shaft of a satellite, and these first and second magnetic torquers 16a and 16b are driven according to accumulative momentum at orbital single round time of a reaction wheel 13 in a driving pattern in which momentum obtained by integrating the torque profile by time over a orbital single round in an inertial coordinate-system becomes maximum. The accumulative momentum equivalent to a single round of the reaction wheel 13 is removed by a relative action between magnetic force caused by the driving and a geomagnetic field, and rotating speed is controlled, and in a condition where the polarity is reversed, generating torque of the first and the second magnetic torquers 16a and 16b is compensated by a feedforward.