Vehicle seat recliner

A recliner that connects a seatback to a base on a floor in a manner in which a backrest angle is adjustable, the recliner comprising:

• one disk-shaped connecting member and another disk-shaped connecting member that are assembled to each other in an axial direction in a state rotatable relative to each other;
• a locking mechanism that is provided between the two connecting members and locks the relative rotation of the two connecting members;
• and
• an outer peripheral ring that is attached straddling an outer peripheral portion of each of the two connecting members and retains the two connecting members in a state assembled to each other in the axial direction, wherein:
• the one connecting member has a smaller outer diameter than the other connecting member does;
• the outer peripheral ring has a joining portion that is joined to the outer peripheral portion of the other connecting member, an abutting portion that is bent radially inward so as to abut against the outer peripheral portion of the one connecting member from an outside in the axial direction, and a connecting portion that connects the joining portion to the abutting portion;
• and
• the connecting portion has a shape in a circumferential direction thereof that extends inclined radially inward from the joining portion toward the abutting portion.