An apparatus for clamping a door trim of a vehicle may include a plurality of clamping portions that are installed on a door trim side and include hooks caught by a door panel side while rotating by tension of a wire, a locking portion that is installed on the door trim side and pulls the wire using a rotating pulley, and the wire that is in a closed loop form between the hooks of the plurality of the clamping portions and the pulley of the locking portion and rotates the hooks while being pulled by the rotation of the pulley.