An emergency door closing device that can be installed upon existing doors and hinges to automatically close doors in the response to smoke and fire. The improvements incorporated therein include a hinge cam pivot member that attaches to an existing hinge member of a door and produces a moment force about the existing hinge member allowing a reduced force necessary to pivot the door into a closed position. Further, a novel spring, cam, and lever system is incorporated to activate the moment force to close the door.