The present disclosure relates to a method for controlling an electric power steering device and a device therefor. More particularly, the present disclosure relates to a method for adjusting a motor torque according to a driver's steering torque when the driver's steering torque is input in a situation where steering of a vehicle is adjusted using only the motor torque. The present disclosure relates to device including at least: an automatic steering mode control unit that controls a steering motor torque, corresponding to automatic steering torque information or automatic steering angle information for running of a vehicle in an automatic steering mode, to be generated when the automatic steering torque information or the automatic steering angle information is received; an automatic steering mode release determination unit that determines whether to release the automatic steering mode when a steering torque or steering angle information generated according to a steering wheel operation of a driver is detected; and an automatic steering mode release unit that determines a release time of the steering motor torque applied in the automatic steering mode, by using the steering angle information generated according to the steering wheel operation of the driver when it is determined to release the automatic steering mode.