Motor control device and a motor system

To provide a motor controller 100 and motor system 10 can be configured robust control system. The motor control device 100 based on the position estimation error is a difference between the motor position and the estimated motor position of the motor 10, the position and speed estimation unit 120 for outputting the estimated motor position and the estimated motor speed, motor estimated position, the estimated motor based on the speed and position command, a control unit 110 which outputs a torque command for controlling the motor, with a position and speed estimation unit 120, the observer corrector 122 to output the observer correction value on the basis of the position estimation error, on the basis of the position estimation error, a nonlinear compensator 124 which outputs a compensation torque based on the observer modification value and the compensation torque, an arithmetic unit 126 for outputting a calculated value based on the calculated value, the estimated motor position and the estimated motor having a motor model 128 of the motor 12 to output a speed, a.