To provide a control device of a steering device capable of discharging large power over a comparatively prolonged period of time, and responding to a request of instantaneously large current.

The control device of a steering device is equipped with a main power source 4 which supplies the power to a motor 1m of a steering device 1s of a vehicle, an electric double-layer capacitor 9a and a secondary battery 9b capable of supplying the power to the motor 1m, and a control circuit 15 which is constituted so as to use the electric double-layer capacitor 9a when the power required for a steering assist of the steering device 1s is larger than a second threshold value, and use the secondary battery 9b when the power is not larger than the second threshold value and larger than the first threshold value.