Abstract: A band-type warning device includes a buckle body, and a light-transmissive strap member with a connecting end connected to one lateral wall of the buckle body. A detachable engaging member includes jaws disposed on the other lateral wall of the buckle body, and an enlarged head portion formed on a detachable end of the strap member. A guiding cleft and a retaining groove are defined by the jaws and the lateral wall such that the head portion can be forced and retained into the retaining groove from the guiding cleft, thereby engaging the detachable end and the buckle body. A lighting element is disposed on at least one of the lateral walls to illuminate the strap member.