To provide a power steering system in which magnetic foreign matter in hydraulic fluid discharged from a hydraulic cylinder is removed and flowing of the magnetic foreign matter into a pump is consequently prevented.

The hydraulic power steering system includes: a hydraulic cylinder disposed in the housing of a rack shaft; a storage tank 60 of hydraulic fluid; an electric pump 50 for supplying the hydraulic fluid from the storage tank 60 to the hydraulic cylinder; and a switch valve 30 for switching supply and discharge of the hydraulic fluid to and from the first oil chamber 23 and the second oil chamber 24 of the hydraulic cylinder. A permanent magnet 45 is disposed in the discharge port 33 of the switch valve 30.