A shift-by-wire control system includes a parking lock device that brings an output shaft of an automatic transmission device to a lock state when a range switching unit switches to the P-range. The parking lock device brings the output shaft to a lock-release state when the range switching unit switches to another shift range. An electric motor actuates the range switching unit and the parking lock device in accordance with an instruction of an operator. A manual device transmits manual operation force of the operator to the parking lock device when the electric motor stops. The manual device includes a one-way transmission unit permitting transmission of the manual operation force in a direction toward the lock state, and prohibiting transmission of the manual operation force in a direction toward the lock-release state.