A system with a motor, a motor control device for controlling said motor, and a dual inertial system arranged to drive a load and comprising a connection to said load via a speed reduction gear, the motor further comprising: a movement command generator that outputs a movement command of the motor; a filter that performs filter processing of the movement command and outputs the filtered movement command; and a position controller that performs a position control of the motor, wherein the filter is an infinite impulse response digital filter that is represented by a transfer function H(z): H(z)=(b0+b1•z -1 +b2•z -2)/{1-(a1•z -1 +a2•z -2)} with filter coefficients a1, a2, b0, b1, and b2, and that outputs output data based on input data input in a plurality of sample periods, wherein the position controller is configured to perform the position control of the motor based on the output data, and characterized in that, the filter is configured, for each of the plurality of sample periods where data is input, to change the filter coefficient b0 in a first sample period among the plurality of sample periods, change the filter coefficients a1 and b1 in a second sample period among the plurality of sample periods which follows the first sample period, and change the filter coefficients a2 and b2 in a third sample period among the plurality of sample periods which follows the second sample period, and, to output output data, for each of the plurality of sample periods, according to intermediate values based on the changed filter coefficients. a movement command generator that outputs a movement command of the motor; a filter that performs filter processing of the movement command and outputs the filtered movement command; and a position controller that performs a position control of the motor, wherein the filter is an infinite impulse response digital filter that is represented by a transfer function H(z): H(z)=(b0+b1•z -1 +b2•z -2)/{1-(a1•z -1 +a2•z -2)} with filter coefficients a1, a2, b0, b1, and b2, and that outputs output data based on input data input in a plurality of sample periods, wherein the position controller is configured to perform the position control of the motor based on the output data, and characterized in that, the filter is configured, for each of the plurality of sample periods where data is input, to change the filter coefficient b0 in a first sample period among the plurality of sample periods, change the filter coefficients a1 and b1 in a second sample period among the plurality of sample periods which follows the first sample period, and change the filter coefficients a2 and b2 in a third sample period among the plurality of sample periods which follows the second sample period, and, change the filter coefficient b0 in a first sample period among the plurality of sample periods, change the filter coefficients a1 and b1 in a second sample period among the plurality of sample periods which follows the first sample period, and change the filter coefficients a2 and b2 in a third sample period among the plurality of sample periods which follows the second sample period, and, to output output data, for each of the plurality of sample periods, according to intermediate values based on the changed filter coefficients.