1. A motor control device, comprising: a current instruction generation unit generating a current instruction based on a torque instruction for a motor; a current detection unit detecting a current that flows in the motor; and a control unit controlling the motor based on a difference between the current instruction and the current detected by the current detection unit; the current instruction generation unit generating, based on the torque instruction, a current instruction having a current phase determined in advance for each torque of the motor so as to suppress vibration of the motor, wherein the current instruction generation unit generates the current instruction so as to restrict variation in a d-axis current with respect to variation in the torque instruction , and the current instruction generation unit generates the current instruction such that the d-axis current monotonously decreases with increase in the torque instruction.