To provide an entanglement accident prevention device which informs a following motor cycle or the like of danger of an entanglement with a clear and rapid means, and prevents the following motor cycle or the like from entering within the range of an inner wheel difference.

The entanglement accident prevention device is equipped with an alarm display device 1, and the alarm display device 1 is stored in a vehicle. The alarm display device 1 is held in an approximately vertical direction of the side surface of turning side of the vehicle based on a turn-on signal of a winker 2 in the case of turning of the vehicle, and constituted so as to be stored in the vehicle based on a turn-off signal of the winker 2.