PURPOSE: To assuredly and easily operate a device by connecting and locking blades in the device for a propeller of a vessel or the like to a boss main body under pressure and supplying high pressure oil so as to temporarily loosen a press connection and adjust the blades.

CONSTITUTION: The flanges 4 of blades 3 are connected to a support disk 5 in a boss 1 by internally inserting a plurality of distortion bolts 6. Then, the blade flanges 4 are locked to the support disk 5 by fitting pins 8. Thus, a structural group 4/5 is locked to the boss 1 under a frictional connection. Pins 11 and sliders 12 for rotating the support disk 5 are arranged in the grooves of adjusting yokes 13. A piston 14 forming a servo motor is connected to the adjusting yokes 13. Then, high pressure oil is introduced to parts between the blade flanges 4 and the support disk 5 through a high pressure oil hole 17 and a high pressure hose 18 to temporarily loosen a lock and adjust the blades 3 by the servo motor.