A drive controller of an instrument controls a stepping motor to rotate a pointer of the instrument attached to a rotation shaft of the stepping motor, the pointer rotatable between a zero scale position and a maximum scale position. The drive controller controls the stepping motor to perform a sweeping operation in which the pointer is swung from the zero scale position to the maximum scale position and returned back to the zero scale position, wherein the drive controller controls the stepping motor, during the sweeping operation, to accelerate to a predetermined speed by outputting a rated torque signal to the stepping motor and controls the stepping motor to rotate at the predetermined speed by outputting a decreased torque signal to the stepping motor, the decreased torque signal being lower than the rated torque signal.