Disclosed herein is a cable coupler for the connection of an armored cable having an armor layer. The cable coupler of the present invention includes a sleeve, which has an inclined surface, which is brought into contact with the armor layer of the armored cable, and a fastening ring and a support ring, each of which has a small width. Each of the fastening ring and the support ring includes inclined surfaces, which are formed by reducing the thickness thereof from a medial portion thereof to opposite ends. The inner inclined surfaces of the fastening ring and the support ring have inclination angles similar to that of the inclined surface of the sleeve. In addition, the armor layer can be firmly held by the cable coupler despite the use of a relatively small force, thus enhancing labor efficiency. As well, armor layers having various thicknesses can be held by the cable coupler merely by changing the positions of the fastening ring and the support ring, thus increasing the usefulness of the cable coupler.