To provide a control device of an electric motor that achieves a desired response characteristic not depending on a constant of a motor apparatus without causing the deterioration of motor speed responsiveness.

In the control device 1 of the electric motor which includes: a speed controller 15 performing the operation of a command current Ia* by using a gain in order to control the speed of a three-phase AC synchronous motor 201, and performing control operations to a D-axis and a Q-axis which are set to the three-phase AC synchronous motor 201; a current distribution part 17; and a current controller 19, the control device also includes a gain creation map 14 which changes the gain in consideration of the change of torque sensitivity with respect to the command value depending on motor speed.