Selectable one-way clutch

A selectable one-way clutch comprising:

• a pocket plate including a plurality of pockets provided along a circumferential direction on one surface of the pocket plate;
• a notch plate that is rotatable with respect to the pocket plate, the notch plate including a plurality of notches provided along a circumferential direction on a surface of the notch plate facing the one surface;
• struts that are plate-shaped and housed in the respective pockets;
• and
• a selector plate disposed between the pocket plate and the notch plate, and configured to switch, by rotating coaxially with the pocket plate, between:
• a state in which the struts have risen toward the notch plate;
• and a state in which the struts are housed in the respective pockets, wherein
• the notch plate includes flat portions between the notches that are adjacent in the circumferential direction, and
• each of the flat portions includes a first recess at a position where the corresponding strut having risen toward the notch plate is brought into contact.