A steering system that is telescopically extendable and retractable using a motor driving force includes a motor, a telescopic steering shaft, a tube that supports the steering shaft such that the steering shaft is rotatable and that is movable with telescopic movement of the steering shaft, and a driving force transmission device that transmits a rotational driving force of the motor to the tube. The driving force transmission device includes a driving force converter that converts the rotational driving force of the motor to a linear driving force, and a coupling member that couples the driving force converter to the tube. The coupling member is breakable by an impact force applied thereto through the steering shaft and the supporting member during a secondary collision so as to decouple the driving force converter from the tube.