To miniaturize a steering system by coaxially arranging a control valve, a steering shaft and a hydraulic cylinder in a housing.

The steering system has a housing 40 which coaxially extends with a steering shaft 30 and assembles the steering shaft 30 in an axially movable and non-turnable manner, and a hollow shaft 50 which is assembled to the housing 40 so as to be turnable to coaxially pass the steering shaft 30. The hollow shaft 50 has a first shaft 51 which is turned as the steering shaft 20 is turned, a second shaft 52 which is connected to the steering shaft 30 via a ball screw mechanism 60, and an elastic part 53 which is elastically and torsionally deformable between the first shaft 51 and the second shaft 52. A control valve 92 for controlling a working fluid supplied to a hydraulic cylinder 91 from a hydraulic pump 93 based on the relative rotation of the first shaft 51 to the second shaft 52 is coaxially interposed between the housing 40 and the hollow shaft 50.