PURPOSE: To satisfy both a resisting feeling produced during neutral operation and a light feeling produced during steering of a steering device by a method wherein a valve mechanism to open and close the communicating hole of each oil pressure chamber is mounted to a piston by which the interior of a power cylinder is divided into a plurality of oil pressure chambers.

CONSTITUTION: A power cylinder 1 is formed such that a piston 4 by which the interior of a cylinder body is divided into a plurality of oil pressure chambers 3a and 3b is slidably disposed in a cylinder body 2 and a rack lever 5 is disposed in a state to be mounted to the piston 4. In this case, a pair of valve mechanisms 6 are mounted to the piston 4 to open and close a pair of communicating holes 7 formed in the piston 4 so as to intercommunicate the oil pressure chambers 3a and 3b. Namely, when a difference in an oil pressure between the oil pressure chambers 3a and 3b exceeds a specified value during lateral steering of a steering device, each communicating hole 7 is closed by each valve mechanism 6.