A spring, provided between a first member and a second member, includes a main body portion having a hole portion; a cylindrical portion provided at the radially inner circumference and the radially outer circumference of the main body portion; and a corner portion formed at a boundary portion between the main body portion and the cylindrical portion; in which the main body portion is extended to a crossing direction with respect to a direction along suppress strength provided from the first member and the second member, the cylindrical portion has an abutting portion protruding from each circumference of the main body portion toward one of the first member and the second member and abutting thereat, the corner portions can be elastically deformed while varying angles thereof according to the suppression strength, and the corner portion defines a tangent line along the main body portion, and at least one of tangent lines of the corner portions makes a predetermined angle with respect to a straight line between the radially inner circumference and the radially outer circumference of the main body portion.