A steer-by-wire steering device comprising: a steering wheel not mechanically connected with a steering shaft for turning; a steering angle sensor for detecting a steering angle of the steering wheel; a steering reactive force motor for applying a reactive force torque to the steering wheel; a steering shaft drive motor for driving the steering shaft; a steering control unit for controlling the steering reactive force motor and the steering shaft drive motor, the steering control unit controlling the steering shaft drive motor on the basis of a driving condition detection signal including a signal indicative of the steering angle detected by the steering angle sensor; a power transmitting mechanism for transmitting a power from the steering shaft drive motor to the steering shaft; and a changeover unit disposed at a location generally intermediate between the power transmitting mechanism and a toe angle adjusting power transmitting mechanism, the changeover unit for switching between a condition for transmitting the power and a condition for interrupting the power; characterized in that the changeover unit includes; a clutch mechanism comprising an input member and an output member (37, 21B) juxtaposed in an axial direction with respective ends thereof held in contact with each other for movement in the axial direction and, also, rotatable relative to each other, a clutch groove provided in one of the input member and the output member (37, 21B) so as to extend axially, a clutch rolling element provided in the other of the input member and the output member (37, 21B) and being selectively engaged and disengaged in and from the clutch groove as biased by an elastic member in a radial direction upon relative movement of the input and output members (38, 37, 21B) in the axial direction, and said one of the input member and the output member (37, 21B) is a shaft member, and the other of the input member and the output member (37, 21B) is a member connected with the shaft member for rotation together therewith and having an engagement hole for engagement with an outer periphery of such one of the members in an axially relatively movable fashion. a steering wheel not mechanically connected with a steering shaft for turning; a steering angle sensor for detecting a steering angle of the steering wheel; a steering reactive force motor for applying a reactive force torque to the steering wheel; a steering shaft drive motor for driving the steering shaft; a steering control unit for controlling the steering reactive force motor and the steering shaft drive motor, the steering control unit controlling the steering shaft drive motor on the basis of a driving condition detection signal including a signal indicative of the steering angle detected by the steering angle sensor; a power transmitting mechanism for transmitting a power from the steering shaft drive motor to the steering shaft; and a changeover unit disposed at a location generally intermediate between the power transmitting mechanism and a toe angle adjusting power transmitting mechanism, the changeover unit for switching between a condition for transmitting the power and a condition for interrupting the power; characterized in that the changeover unit includes; a clutch mechanism comprising an input member and an output member (37, 21B) juxtaposed in an axial direction with respective ends thereof held in contact with each other for movement in the axial direction and, also, rotatable relative to each other, a clutch groove provided in one of the input member and the output member (37, 21B) so as to extend axially, a clutch rolling element provided in the other of the input member and the output member (37, 21B) and being selectively engaged and disengaged in and from the clutch groove as biased by an elastic member in a radial direction upon relative movement of the input and output members (38, 37, 21B) in the axial direction, and said one of the input member and the output member (37, 21B) is a shaft member, and the other of the input member and the output member (37, 21B) is a member connected with the shaft member for rotation together therewith and having an engagement hole for engagement with an outer periphery of such one of the members in an axially relatively movable fashion.