Abstract: An unlocking-resistant and loosening-resistant nut assembly includes a conic nut and a wedge washer. The conic nut includes a conic portion, a force application portion, and a first wedge face formed on a bottom surface of the conic nut. The force application portion includes a hexagonal prism to enable force application thereto by a socket or open-ended wrench. The conic portion has a curved contour that shows a concave curve. The wedge washer includes a circular washer having a diameter greater than the conic nut. The wedge washer has a surface on which a second wedge face that corresponds in configuration to the first wedge face of the conic nut is circumferentially formed and an opposite surface forming at least one sharp fitting rib that has a cross-section comprising a right-angle having a hypotenuse extending in the direction of tightening the conic nut.