A selectable one-way clutch includes: a pocket plate; struts; a notch plate having a plurality of notches; and a selector plate that has a plurality of window holes. The strut includes a protrusion formed at a center thereof in a radial direction of the selectable one-way clutch. The selector plate has a cutout groove extending from an inner surface of the window hole along a formation direction of the protrusion. When the selectable one-way clutch is disengaged, the cutout groove is fitted on the protrusion, and the strut and the selector plate overlap each other in a rotational axis direction of the selectable one-way clutch.