A wave generator for a strain wave gearing device, comprising: a wave generator plug provided with an ellipsoidal external peripheral surface; and a wave generator bearing mounted and secured to the ellipsoidal external peripheral surface and caused to flex into an ellipsoidal shape, wherein the wave generator bearing has an outer race and inner race capable of flexing in a radial direction, and a plurality of rolling elements inserted in a rollable state between the outer race and the inner race; characterized in that an inner-race lubrication groove pattern comprising first lubrication grooves and second lubrication grooves is formed in an inner-race raceway surface of the inner race; an outer-race lubrication groove pattern comprising third lubrication grooves is formed in an outer-race raceway surface of the outer race; the first, second, and third lubrication grooves (52,54, 60) are linear grooves and extend in straight lines, curved lines, or a wave-like form; the inner-race lubrication groove pattern includes a first groove pattern and a second groove pattern; in the inner-race raceway surface, the first groove pattern of the inner-race lubrication groove pattern is formed in short-axis-side inner-race raceway surface portions (46A1, 46A2) including positions on a short axis (Lmin) of the ellipsoidal shape, and the second groove pattern of the inner-race lubrication groove pattern is formed in long-axis-side inner-race raceway surface portions (46B1, 46B2) including positions on a long axis (Lmax) of the ellipsoidal shape; and in the first groove pattern, the first lubrication grooves extend so that a direction in which the first lubrication grooves are aligned includes a directional component facing a circumferential direction of the inner-race raceway surface; wherein the first groove pattern of the inner-race lubrication groove pattern comprises the first lubrication grooves extending in the circumferential direction of the inner-race raceway surface; the second groove pattern comprises the second lubrication grooves extending in the width direction of the inner-race raceway surface; and the outer-race lubrication groove pattern comprises the third lubrication grooves extending in the width direction of the outer-race raceway surface. a wave generator plug provided with an ellipsoidal external peripheral surface; and a wave generator bearing mounted and secured to the ellipsoidal external peripheral surface and caused to flex into an ellipsoidal shape, wherein the wave generator bearing has an outer race and inner race capable of flexing in a radial direction, and a plurality of rolling elements inserted in a rollable state between the outer race and the inner race; characterized in that an inner-race lubrication groove pattern comprising first lubrication grooves and second lubrication grooves is formed in an inner-race raceway surface of the inner race; an outer-race lubrication groove pattern comprising third lubrication grooves is formed in an outer-race raceway surface of the outer race; the first, second, and third lubrication grooves (52,54, 60) are linear grooves and extend in straight lines, curved lines, or a wave-like form; the inner-race lubrication groove pattern includes a first groove pattern and a second groove pattern; in the inner-race raceway surface, the first groove pattern of the inner-race lubrication groove pattern is formed in short-axis-side inner-race raceway surface portions (46A1, 46A2) including positions on a short axis (Lmin) of the ellipsoidal shape, and the second groove pattern of the inner-race lubrication groove pattern is formed in long-axis-side inner-race raceway surface portions (46B1, 46B2) including positions on a long axis (Lmax) of the ellipsoidal shape; and in the first groove pattern, the first lubrication grooves extend so that a direction in which the first lubrication grooves are aligned includes a directional component facing a circumferential direction of the inner-race raceway surface; wherein the first groove pattern of the inner-race lubrication groove pattern comprises the first lubrication grooves extending in the circumferential direction of the inner-race raceway surface; the second groove pattern comprises the second lubrication grooves extending in the width direction of the inner-race raceway surface; and the outer-race lubrication groove pattern comprises the third lubrication grooves extending in the width direction of the outer-race raceway surface.