A vehicle steering system in which a steering member that is allowed to be rotated 360 degrees or more and a steered wheel are not mechanically coupled to each other, comprising: a steering angle sensor that detects a steering angle (δh) of the steering member; a steering system actuator that drives the steered wheel; characterized by a rotation angle restriction mechanism that is switchable between a first state in which a rotation angle of the steering member is restricted within a first rotation angular range (δmax) that is larger than or equal to 360 degrees and a second state in which the rotation angle of the steering member is restricted within a second rotation angular range (δ2) that is smaller than 360 degrees; a switching mechanism that selectively switches the rotation angle restriction mechanism into the first state or the second state; a steering direction detection unit that, when the rotation angle restriction mechanism is in the second state, detects a steering direction of the steering member on the basis of at which one of a pair of terminal ends of the second rotation angular range (δ2), the steering member is located; and a control unit that has a normal mode in which drive control is executed on the steering system actuator on the basis of the steering angle (θh) detected by the steering angle sensor and a failure mode in which, when there is a malfunction in the steering angle sensor, drive control is executed on the steering system actuator on the basis of the steering direction detected by the steering direction detection unit in a state where the rotation angle restriction mechanism is switched into the second state by the switching mechanism. a steering angle sensor that detects a steering angle (δh) of the steering member; a steering system actuator that drives the steered wheel; characterized by a rotation angle restriction mechanism that is switchable between a first state in which a rotation angle of the steering member is restricted within a first rotation angular range (δmax) that is larger than or equal to 360 degrees and a second state in which the rotation angle of the steering member is restricted within a second rotation angular range (δ2) that is smaller than 360 degrees; a switching mechanism that selectively switches the rotation angle restriction mechanism into the first state or the second state; a steering direction detection unit that, when the rotation angle restriction mechanism is in the second state, detects a steering direction of the steering member on the basis of at which one of a pair of terminal ends of the second rotation angular range (δ2), the steering member is located; and a control unit that has a normal mode in which drive control is executed on the steering system actuator on the basis of the steering angle (θh) detected by the steering angle sensor and a failure mode in which, when there is a malfunction in the steering angle sensor, drive control is executed on the steering system actuator on the basis of the steering direction detected by the steering direction detection unit in a state where the rotation angle restriction mechanism is switched into the second state by the switching mechanism.