SEATBELT DEVICE OF VEHICLE

A seat belt apparatus of a vehicle described in the present disclosure includes a seat belt coupled to a seat and including a webbing comprising a detectable material; a vision sensor configured to generate an image by capturing a field of view region including the seat; and a monitoring system configured to detect a length of the webbing e.g., based on the pattern coated with the at least one paint in the image, and determine whether a user wears the seat belt as desired or erroneously wears the seat belt based on the detected length of the webbing.