A control device for an electric power steering device that applies an auxiliary steering force to a steering mechanism of a vehicle by a rotational force of a motor, comprising: a vehicle-side ECU, which comprises a vehicle motion control section which calculates a steering angle command value θref based on a target value of the vehicle and modifies a target value for a lateral position of the vehicle when disturbance such as crosswind occurs, where the steering angle command value θref calculated in the vehicle motion control section is input to a steering angle control section in an EPS-side ECU; and the EPS-side ECU, which comprises: the steering angle control section which controls a steering angle of the steering mechanism based on an input steering angle command value θref; and a switching determination/gradual change gain generating section which generates gradual change gains, by which steering angle control output from the steering angle control section and assist control output from an assist control section are multiplied, and multiplies the gradual change gains to make a determination to switch between a steering angle control mode by the steering angle control section and an assist control mode by the assist control section, characterized in that the steering angle control section comprises: a steering angle calculating section (201, 201a) which outputs a detected steering-wheel angle θh as an actual steering angle θr when an input steering angle abnormality determination signal indicates normal, or determines an estimate θr of an actual steering angle of the steering mechanism using a past value Zθm of an input motor angle and outputs the estimate θr as an actual steering angle estimate θr when the steering angle abnormality determination signal indicates abnormal; and a position control section which derives a steering angular velocity command value ωref based on an input target steering angle θt and the actual steering angle θr or the actual steering angle estimate θr. a vehicle-side ECU, which comprises a vehicle motion control section which calculates a steering angle command value θref based on a target value of the vehicle and modifies a target value for a lateral position of the vehicle when disturbance such as crosswind occurs, where the steering angle command value θref calculated in the vehicle motion control section is input to a steering angle control section in an EPS-side ECU; and the EPS-side ECU, which comprises: the steering angle control section which controls a steering angle of the steering mechanism based on an input steering angle command value θref; and a switching determination/gradual change gain generating section which generates gradual change gains, by which steering angle control output from the steering angle control section and assist control output from an assist control section are multiplied, and multiplies the gradual change gains to make a determination to switch between a steering angle control mode by the steering angle control section and an assist control mode by the assist control section, the steering angle control section which controls a steering angle of the steering mechanism based on an input steering angle command value θref; and a switching determination/gradual change gain generating section which generates gradual change gains, by which steering angle control output from the steering angle control section and assist control output from an assist control section are multiplied, and multiplies the gradual change gains to make a determination to switch between a steering angle control mode by the steering angle control section and an assist control mode by the assist control section, characterized in that the steering angle control section comprises: a steering angle calculating section (201, 201a) which outputs a detected steering-wheel angle θh as an actual steering angle θr when an input steering angle abnormality determination signal indicates normal, or determines an estimate θr of an actual steering angle of the steering mechanism using a past value Zθm of an input motor angle and outputs the estimate θr as an actual steering angle estimate θr when the steering angle abnormality determination signal indicates abnormal; and a position control section which derives a steering angular velocity command value ωref based on an input target steering angle θt and the actual steering angle θr or the actual steering angle estimate θr. a steering angle calculating section (201, 201a) which outputs a detected steering-wheel angle θh as an actual steering angle θr when an input steering angle abnormality determination signal indicates normal, or determines an estimate θr of an actual steering angle of the steering mechanism using a past value Zθm of an input motor angle and outputs the estimate θr as an actual steering angle estimate θr when the steering angle abnormality determination signal indicates abnormal; and a position control section which derives a steering angular velocity command value ωref based on an input target steering angle θt and the actual steering angle θr or the actual steering angle estimate θr.