PURPOSE: To constitute a device, which is constituted to sequentially actuate a side clutch and a side brake by way of sliding a slave rotary body of a hydraulic actuation type steering system, compact as a whole by way of improving arrangement of a piston to slide the slave rotary body.

CONSTITUTION: A cylindrical part 1d storing a piston 41 to slide a slave rotary body 33L in the releasing direction is provided to face an outer peripheral position of a slave rotary body 33 by way of fixing it integrally with a mission case 1 or on if and a tooth part 33La of the slave rotary body 33L can slide inside of a cylinder upper part 1d at the time when a side brake is actuated.