A washer comprising: an inner peripheral face formed in an arc shape; an outer peripheral face formed in an arc shape concentric with the inner peripheral face on a radially outer side of the inner peripheral face; an outer peripheral cut-out portion (15L, 15R) formed at a position of the outer peripheral face corresponding to an end portion of the inner peripheral face to have the same shape as an outside shape of the corresponding end portion of the inner peripheral face; an inner peripheral cut-out portion (14L, 14R) formed at the end portion of the inner peripheral face; an one end face connecting one end of the inner peripheral face with one end of the outer peripheral face; and the other end face connecting the other end of the inner peripheral face with the other end of the outer peripheral face, wherein the one end face and the other end face are formed along an imaginary straight line passing through an arc center of the inner peripheral face and the outer peripheral face, an imaginary line (Ls) is perpendicular to the first imaginary line and crosses the arc center, and the inner peripheral cut-out portion (14L, 14R) includes: a first inner peripheral cut-out portion formed at one of opposite end portions of the inner peripheral face, and a second inner peripheral cut-out portion formed at the other of the opposite end portions of the inner peripheral face so that the first inner peripheral cut-out portion and the second inner peripheral cut-out portion are asymmetric in shape, wherein the first inner peripheral cut-out portion and the second inner peripheral cut-out portion are formed along the same circumference, and an arc center of the circumference is offset with respect to the imaginary line (Ls) along an imaginary line parallel to the first imaginary line. an inner peripheral face formed in an arc shape; an outer peripheral face formed in an arc shape concentric with the inner peripheral face on a radially outer side of the inner peripheral face; an outer peripheral cut-out portion (15L, 15R) formed at a position of the outer peripheral face corresponding to an end portion of the inner peripheral face to have the same shape as an outside shape of the corresponding end portion of the inner peripheral face; an inner peripheral cut-out portion (14L, 14R) formed at the end portion of the inner peripheral face; an one end face connecting one end of the inner peripheral face with one end of the outer peripheral face; and the other end face connecting the other end of the inner peripheral face with the other end of the outer peripheral face, wherein the one end face and the other end face are formed along an imaginary straight line passing through an arc center of the inner peripheral face and the outer peripheral face, an imaginary line (Ls) is perpendicular to the first imaginary line and crosses the arc center, and the inner peripheral cut-out portion (14L, 14R) includes: a first inner peripheral cut-out portion formed at one of opposite end portions of the inner peripheral face, and a second inner peripheral cut-out portion formed at the other of the opposite end portions of the inner peripheral face so that the first inner peripheral cut-out portion and the second inner peripheral cut-out portion are asymmetric in shape, a first inner peripheral cut-out portion formed at one of opposite end portions of the inner peripheral face, and a second inner peripheral cut-out portion formed at the other of the opposite end portions of the inner peripheral face so that the first inner peripheral cut-out portion and the second inner peripheral cut-out portion are asymmetric in shape, wherein the first inner peripheral cut-out portion and the second inner peripheral cut-out portion are formed along the same circumference, and