A supply passage is formed in a rotary shaft along the axis thereof. An expansion passage is formed in the rotary shaft in such a way as to be led to the supply passage. A pair of fluid passages are formed in the rotary shaft in such a way as to communicate with the expansion passage. The fluid passages extend in a direction orthogonal to the axis and the outlet ports of the fluid passages are open to the outer surface of the rotary shaft. The fluid passages extend from the expansion passage to a control pressure chamber, penetrating through the rotary shaft.