Abstract: A sink drain plug is composed of a main body, a cover body, a center rod, a pull head, and an elastic wire body. The main body is fastened with a sink or lavatory. The cover body is located on the top of the main body and is provided with a hollow column extending from the underside thereof. The center rod is fitted into the hollow column such that the center rod is fastened at the bottom end thereof with the bottom end of the main body. The pull head is fastened with the top of the cover body. The elastic wire body is engaged with the center rod such that two lugs of the elastic wire body are jutted out of the center rod to urge the inside of the hollow column so as to locate securely the cover body at a level at which the main body is opened or closed.