A steer-by-wire steering device includes a steering wheel connected with a steering shaft, a steering angle sensor, a steering reactive force motor, and a steering control unit for controlling a steering shaft drive motor and the steering reactive force motor. Provided is a power transmitting mechanism for transmitting the power from the steering shaft drive motor to the steering shaft. A changeover unit for selectively connecting and disconnecting the power is disposed on the way thereof. The changeover unit includes a clutch mechanism comprised of an input member and an output member juxtaposed in an axial direction for movement in the axial direction and, also, rotatable relative to each other, a clutch groove provided in one of those members, and a clutch rolling element provided in the other of those members and biased in a radial direction by the clutch groove so that it can be selectively engaged and disengaged.