The present invention provides to a cable anchorage device capable of obtaining structural safety of a cable anchorage device by controlling deformation of an opening anchorage unit as the deformation (d) of an opening is excessively generated when a fracture form of the cable anchorage device is considered. The cable anchorage device including a strain prevention key in accordance with the present invention comprises a cable; a coupler in which the cable is inserted; the opening anchorage unit which is screwed with the coupler and includes an opening unit of which both upper parts protrude at a fixed length; a connection pin installed to cross between the opening unit and a fixing block; and the strain prevention key which is located to the upper part of the connection pin and crossing between the opening unit and the fixing block.
