A vane compressor comprising: - an approximately cylindrical cylinder whose both axial ends are open; - a frame that closes one axial end of the cylinder; - a cylinder head that closes the other axial end of the cylinder; - a rotor shaft including a columnar rotor portion that rotates in the cylinder about a central axis that is eccentric to the central axis of an inner peripheral surface of the cylinder, and a shaft portion (4b, 4c) that transmits torque to the rotor portion and is supported by the frame and cylinder head; and - a plurality of vanes (9, 10) installed in the rotor portion, each of the plurality of vanes (9, 10) having a tip portion (9a, 10a) formed into a circular arc shape facing outward, wherein - each of the plurality of vanes (9, 10) is held to be constantly in a normal direction of an inner peripheral surface of the cylinder or is held to constantly have a fixed inclination with respect to the normal direction of the inner peripheral surface of the cylinder so that a compression operation is performed in a state where a normal to the circular arc shape formed by the tip portion (9a, 10a) of each of the plurality of vanes (9, 10) and a normal to the inner peripheral surface of the cylinder are constantly coincident with each other, - the plurality of vanes (9, 10) are rotatably and movably supported with respect to the rotor portion in the rotor portion, - a concave portion or a ring-shaped groove (2a, 3a) being concentric with an inner diameter of the cylinder is formed in an end surface of each of the cylinder head and the frame on a side of the cylinder, and characterised in that a pair of partial ring-shaped vane aligners (5, 6, 7, 8) unitarily formed with the plurality of vanes (9, 10) is fitted in the concave portion or the ring-shaped groove (2a, 3a), such that a minute space is maintained between the tip portion (9a, 10a) of each of the plurality of vanes (9, 10) and the inner peripheral surface of the cylinder. - an approximately cylindrical cylinder whose both axial ends are open; - a frame that closes one axial end of the cylinder; - a cylinder head that closes the other axial end of the cylinder; - a rotor shaft including a columnar rotor portion that rotates in the cylinder about a central axis that is eccentric to the central axis of an inner peripheral surface of the cylinder, and a shaft portion (4b, 4c) that transmits torque to the rotor portion and is supported by the frame and cylinder head; and - a plurality of vanes (9, 10) installed in the rotor portion, each of the plurality of vanes (9, 10) having a tip portion (9a, 10a) formed into a circular arc shape facing outward, wherein - each of the plurality of vanes (9, 10) is held to be constantly in a normal direction of an inner peripheral surface of the cylinder or is held to constantly have a fixed inclination with respect to the normal direction of the inner peripheral surface of the cylinder so that a compression operation is performed in a state where a normal to the circular arc shape formed by the tip portion (9a, 10a) of each of the plurality of vanes (9, 10) and a normal to the inner peripheral surface of the cylinder are constantly coincident with each other, - the plurality of vanes (9, 10) are rotatably and movably supported with respect to the rotor portion in the rotor portion, - a concave portion or a ring-shaped groove (2a, 3a) being concentric with an inner diameter of the cylinder is formed in an end surface of each of the cylinder head and the frame on a side of the cylinder, and characterised in that