Abstract: A wave spring, in which a multiply annularly wound spring comprises a wave portion in which peaks and troughs are alternately formed in a winding peripheral direction and a ring-like mounting portion that is substantially flat in the winding peripheral direction, with an inner periphery or an outer periphery of the mounting portion being mounted upon engaging with an outer periphery or an inner periphery of an member to be mounted, wherein the outer periphery or the inner periphery of the mounting portion is provided with an engaging urging portion which enables engagement through elastic contact with respect to a radial direction.