Rotation locking device

A rotation locking device, comprising:

• a locking gear having engaging concave portions at a plurality of locations in a circumferential direction thereof;
• a reverse input blocking clutch having an input member, and an output member arranged coaxially with each other, and in a case where rotational torque is inputted to the input member, transmits the rotational torque inputted to the input member to the output member, and in a case where rotational torque is reversely inputted to the output member, does not transmit the rotational torque inputted to the output member to the input member;
• and
• an engaging member having an engaging claw portion capable of engaging in an engaging concave portion of the engaging concave portions, and is rotatably supported by the output member;
• the rotation locking device switching between a first mode where the engaging claw portion engages with the engaging concave portion by the output member rotating the engaging member due to the input member being rotationally driven, and rotation of the locking gear is restricted, and a second mode where engagement between the engaging claw portion and the engaging concave portion is released and rotation of the locking gear is allowed.