Wave washer, rotary shaft supporting device including the wave washer, and electric motor including the rotary shaft supporting device

A wave washer, comprising:

• an annular portion having a first protrusion that protrudes toward one side only in an axial direction of the wave washer, and a second protrusion that is formed so as to be continuous with the first protrusion and that protrudes toward the other side only in an axial direction;
• and
• a plurality of outward protrusions that protrude outward from an outer periphery of the annular portion in a radial direction of the annular portion, wherein
• the annular portion has inner periphery concave portions that are formed at portions radially inward of portions at which the outward protrusions are formed;
• the inner periphery concave portions have recessed portions in a plane perpendicular to the axial direction away from a center of the annular portion radially outwardly toward the outward protrusions;
• a maximum radially recessed amount of each of the inner periphery concave portions is equal to a maximum radially protruded amount of each of the outward protrusions.