Method of manufacturing washer and washer

A method of manufacturing a washer, the method comprising:

• a preparing step of preparing a panel-shaped member comprising a sliding portion capable of sliding against another member;
• a cutting step of cutting the panel-shaped member with the sliding portion with a laser to thereby obtain a longitudinal member that includes a part of the sliding portion, the longitudinal member having longitudinal side edges on opposite sides of the longitudinal member, the longitudinal side edges extending in a direction in which the laser is applied, the longitudinal side edges of the longitudinal member having arc shaped peak portions and arc shaped trough portions adjacent to the peak portions formed alternately and continuously in the longitudinal direction, wherein the part of the sliding portion on the longitudinal member extends from one of the longitudinal side edges to another of the longitudinal side edges, and forms at least a part of the longitudinal side edges on opposite sides of the longitudinal member, and the portions of the longitudinal side edges that are formed of the sliding portion have a higher hardness than a portion of the sliding portion that is between the longitudinal side edges;
• and
• a forming step of forming the longitudinal member into an arc-shaped washer, such that one of the longitudinal side edges forms an outer peripheral side of the arc-shaped washer, and another of the longitudinal side edges forms an inner peripheral side of the arc-shaped washer, the arc-shaped washer having the peak portions and the trough portions formed alternately and continuously in the circumferential direction in the outer peripheral side and the inner peripheral side, by bending and deforming the longitudinal member.