PURPOSE: To prevent noise and enhance the sealing property of a sealing member and durability of a variable displacement vane pump by forming a portion of the outer peripheral face of a cam ring roughly opposite to a pivot pin into a circular face whose center is the center of the pivot pin, and forming a pressure chamber between the circular face and the inner peripheral face of pump housing.

CONSTITUTION: Semicircular recessed portions 23a, 18 opposite to each other are formed in the outer peripheral face 22 of a cam ring 2 and the peripheral face 15 of a pump- housing inner cavity 1c, respectively, and a pivot roller 23 is fitted in between the recessed portions 23a, 18 and the surface 22a of the outer peripheral face 22 of the cam ring is formed into a circular face whose center is the center O2 of the pivot roller 23 and a sealing member 5 is interposed between the outer peripheral face 22 and the inner peripheral face 15 of pump housing and a first control pressure chamber 91 is provided on one side of a space being divided into two and a second control pressure chamber 92 is provided on the other side. The space surrounded by the inner peripheral face 21 of the cam ring 2, the outer peripheral face 32 of a rotor 3 and the inner peripheral face of the pump housing is divided by a vane 4 and the capacity of a pump chamber 6 located in the space is increased or decreased as the rotor 3 is rotated.