A vehicle steering system comprising: an electric motor to provide a steering force to a steering operation mechanism of a vehicle; an automatic steering controller configured to set, in accordance with an angle difference (Δθ) between a target steering angle (θ*) and an actual steering angle (θ), a target automatic steering torque (Tad*) to reduce the angle difference (Δθ) to zero, and configured to control the electric motor in accordance with the target automatic steering torque (Tad*) so as to carry out automatic steering control; a manual steering controller configured to control the electric motor in accordance with a target assist torque (Tmd*) responsive to a steering torque (Td) so as to carry out manual steering control; and an automatic steering deactivator configured to change the automatic steering control to the manual steering control in response to a steering operation performed by a driver during the automatic steering control carried out by the automatic steering controller, characterized in that the automatic steering deactivator includes a transition controller configured to calculate a target motor torque (Tm*) by assigning a weight to each of the target automatic steering torque (Tad*) and the target assist torque (Tmd*) using the angle difference (Δθ) upon satisfaction of a transition control start requirement including at least a requirement that an absolute value (|Td|) of the steering torque (Td) is equal to or greater than a first predetermined value (Tth), and configured to control the electric motor in accordance with the target motor torque (Tm*) so as to carry out transition control, and a changer configured to end the transition control and change the automatic steering control to the manual steering control when an absolute value (|Δθ|) of the angle difference (Δθ) is greater than a second predetermined value (w). an electric motor to provide a steering force to a steering operation mechanism of a vehicle; an automatic steering controller configured to set, in accordance with an angle difference (Δθ) between a target steering angle (θ*) and an actual steering angle (θ), a target automatic steering torque (Tad*) to reduce the angle difference (Δθ) to zero, and configured to control the electric motor in accordance with the target automatic steering torque (Tad*) so as to carry out automatic steering control; a manual steering controller configured to control the electric motor in accordance with a target assist torque (Tmd*) responsive to a steering torque (Td) so as to carry out manual steering control; and an automatic steering deactivator configured to change the automatic steering control to the manual steering control in response to a steering operation performed by a driver during the automatic steering control carried out by the automatic steering controller, a transition controller configured to calculate a target motor torque (Tm*) by assigning a weight to each of the target automatic steering torque (Tad*) and the target assist torque (Tmd*) using the angle difference (Δθ) upon satisfaction of a transition control start requirement including at least a requirement that an absolute value (|Td|) of the steering torque (Td) is equal to or greater than a first predetermined value (Tth), and configured to control the electric motor in accordance with the target motor torque (Tm*) so as to carry out transition control, and a changer configured to end the transition control and change the automatic steering control to the manual steering control when an absolute value (|Δθ|) of the angle difference (Δθ) is greater than a second predetermined value (w). <EOS>