Provided is a propeller rotor in which it is possible to vary the size of the blades of the rotor in a hydroelectric generator installed in a small water channel, as necessary and according to the local situation. In the horizontal shaft rotor of a hydraulic turbine device, a the of the blade mounting parts are formed so as to radiate outward, on the peripheral surface the rear of the hub (2), andthe device is formed in such a manner that the mounting parts (5B) of the blade can be Mounted to the blade mounting parts (3) even if the mounting parts (5B) of the blades are reversed in a front and rear direction.