ROTATION LOCK DEVICE

A structure of a rotation locking device that is easily configured and capable of keeping cost down is achieved. [0002] A rotation locking device 4 switches between a first mode where an engaging claw portion 14 engages with an engaging concave portion 9 by an output member 13 rotating an engaging member 8 due to an input member 12 being rotationally driven by an actuator 7, and rotation of a locking gear 5 supported by and fixed to an output shaft 3 of an automatic transmission 2 is restricted, and a second mode where engagement between the engaging claw portion 14 and the engaging concave portion 9 is released and rotation of the locking gear 5 is allowed.