A flexible display device comprising: a first body and a first frame coupled to the first body; a second body configured to be relatively movable with respect to the first body and a second frame coupled to the second body; a flexible display disposed on a front side of the first body and a rear side of the second body, and a size of a first area of the flexible display exposed to the front side and a size of a second area of the flexible display exposed to the rear side are variable according to relative movement of the second body with respect to the first body; and a rotating bending bar disposed on the first frame and at least a portion inserted into the second frame to couple the first frame and the second frame, and rotated when changing from one of a first state and the second state to the other as the second body slides toward or away from the first body, wherein the first state in which an area of the flexible display exposed to the rear part of the second body is maximized and the second state in which an area of the flexible display exposed to the front part of the first body is maximized; wherein the rotating bending bar comprises: a rotation shaft that is a rotation center of the rotating bending bar; a locking protrusion protruding from the rotation shaft toward the second frame; and a locking hook protruding from the rotation shaft and bent to extend in a direction away from the second frame, and wherein the first frame on which the rotation axis is disposed comprises: a first groove where the rotation shaft is inserted and the inserted rotation shaft is rotated; and a second groove providing a space in which the locking hook rotates. a first body and a first frame coupled to the first body; a second body configured to be relatively movable with respect to the first body and a second frame coupled to the second body; a flexible display disposed on a front side of the first body and a rear side of the second body, and a size of a first area of the flexible display exposed to the front side and a size of a second area of the flexible display exposed to the rear side are variable according to relative movement of the second body with respect to the first body; and a rotating bending bar disposed on the first frame and at least a portion inserted into the second frame to couple the first frame and the second frame, and rotated when changing from one of a first state and the second state to the other as the second body slides toward or away from the first body, wherein the first state in which an area of the flexible display exposed to the rear part of the second body is maximized and the second state in which an area of the flexible display exposed to the front part of the first body is maximized; wherein the rotating bending bar comprises: a rotation shaft that is a rotation center of the rotating bending bar; a locking protrusion protruding from the rotation shaft toward the second frame; and a locking hook protruding from the rotation shaft and bent to extend in a direction away from the second frame, and wherein the first frame on which the rotation axis is disposed comprises: a first groove where the rotation shaft is inserted and the inserted rotation shaft is rotated; and a second groove providing a space in which the locking hook rotates. a rotation shaft that is a rotation center of the rotating bending bar; a locking protrusion protruding from the rotation shaft toward the second frame; and a locking hook protruding from the rotation shaft and bent to extend in a direction away from the second frame, and wherein the first frame on which the rotation axis is disposed comprises: a first groove where the rotation shaft is inserted and the inserted rotation shaft is rotated; and a second groove providing a space in which the locking hook rotates. a first groove where the rotation shaft is inserted and the inserted rotation shaft is rotated; and a second groove providing a space in which the locking hook rotates.