A steering system comprising: a steering actuator configured to operate such that a steering reaction force is applied to a steering wheel of a vehicle, using electric power supplied from a first power supply mounted in the vehicle, the vehicle having a start switch such as an ignition switch; and a turning actuator having a structure in which a power transmission path between the turning actuator and the steering actuator is cut off, the turning actuator being configured to operate such that turning wheels of the vehicle are turned, using the electric power supplied from the first power supply, wherein the steering system is configured such that electric power is supplied to the steering actuator and the turning actuator from the first power supply when a power state of the vehicle is an on state and supply of the electric power from the first power supply is cut off when the power state is an off state, the power state being the on state when the start switch is in the on state, the power state being the off state when the start switch is in the off state, and wherein the steering system further includes a rotation curbing unit configured to operate such that rotation of the steering wheel is curbed in at least a part of a first power-off period from when the power state becomes the off state until when the power state becomes the on state next, as an operating period, and a second power supply configured to supply, to the rotation curbing unit, the electric power required for operation of the rotation curbing unit in the operating period, the second power supply being different from the first power supply. a steering actuator configured to operate such that a steering reaction force is applied to a steering wheel of a vehicle, using electric power supplied from a first power supply mounted in the vehicle, the vehicle having a start switch such as an ignition switch; and a turning actuator having a structure in which a power transmission path between the turning actuator and the steering actuator is cut off, the turning actuator being configured to operate such that turning wheels of the vehicle are turned, using the electric power supplied from the first power supply, wherein the steering system is configured such that electric power is supplied to the steering actuator and the turning actuator from the first power supply when a power state of the vehicle is an on state and supply of the electric power from the first power supply is cut off when the power state is an off state, the power state being the on state when the start switch is in the on state, the power state being the off state when the start switch is in the off state, and wherein the steering system further includes a rotation curbing unit configured to operate such that rotation of the steering wheel is curbed in at least a part of a first power-off period from when the power state becomes the off state until when the power state becomes the on state next, as an operating period, and a second power supply configured to supply, to the rotation curbing unit, the electric power required for operation of the rotation curbing unit in the operating period, the second power supply being different from the first power supply. a rotation curbing unit configured to operate such that rotation of the steering wheel is curbed in at least a part of a first power-off period from when the power state becomes the off state until when the power state becomes the on state next, as an operating period, and a second power supply configured to supply, to the rotation curbing unit, the electric power required for operation of the rotation curbing unit in the operating period, the second power supply being different from the first power supply.