Abstract: Disclosed is a necktie. The necktie has two strips, and a knotting part and a neck surrounding part formed with the two strips. A detachable part, having a hook part and a pile part of Velcro respectively attached to opposite ends of the neck surrounding part, is used for setting the necktie around one's neck. A shape retaining piece, formed with a piece of plastic, is set into the knotting part, for allowing the knotting part to have a convex surface. The tie also has a hanging portion having a leading end and a trailing end of a triangular shape, and representing a trapezoid in shape tapered from the leading end to the trailing end. A length adjusting unit is set into the knotting part, capable of adjusting the length of a hanging portion, including a main body supporting the hanging portion. Two insert parts are formed on terminals of the adjusting unit, for being inserted into the knotting part.