A flexible display device comprising: a display unit; a support unit configured to selectively support the display unit; a connection unit configured to attached together one edge of the display unit and one edge of the support unit; and a driving unit connected to the other edge of the display unit and the other edge of the support unit and configured to control a plurality of operations, wherein the plurality of operations includes a first operation which allows the display unit and the support unit to come in contact with each other to maintain a flattened state of the display unit, and a second operation which enables the display unit and the support unit to be separated from each other for stowage. wherein the first operation allows a back surface of the display unit and a back surface of the support unit to come in contact with each other with gradually increasing their surface contact area under control of the driving unit, and the second operation enables the back surface of the display unit and the back surface of the support unit to be separated from each other with gradually decreasing their surface contact area under control of the driving unit, wherein the driving unit includes: a first driving means configured to drive the display unit and a second driving means configured to drive the support unit, and wherein the first driving means and the second driving means rotate along rotation directions opposite to each other during the first operation or second operation, wherein the first driving means are configured to roll or unroll the display unit and the second driving means are configured to roll or unroll the support unit, wherein the display unit and the support unit are rolled and unrolled together by the first driving means and the second driving means operating simultaneously, and wherein the support unit has a thickness such that its restoring force bending the support unit in one side direction is equal to a restoring force bending the display unit in another side direction when the display unit and the support unit are rolled out. a display unit; a support unit configured to selectively support the display unit; a connection unit configured to attached together one edge of the display unit and one edge of the support unit; and a driving unit connected to the other edge of the display unit and the other edge of the support unit and configured to control a plurality of operations, wherein the plurality of operations includes a first operation which allows the display unit and the support unit to come in contact with each other to maintain a flattened state of the display unit, and a second operation which enables the display unit and the support unit to be separated from each other for stowage. wherein the first operation allows a back surface of the display unit and a back surface of the support unit to come in contact with each other with gradually increasing their surface contact area under control of the driving unit, and the second operation enables the back surface of the display unit and the back surface of the support unit to be separated from each other with gradually decreasing their surface contact area under control of the driving unit, a first driving means configured to drive the display unit and a second driving means configured to drive the support unit, and wherein the first driving means and the second driving means rotate along rotation directions opposite to each other during the first operation or second operation, wherein the first driving means are configured to roll or unroll the display unit and the second driving means are configured to roll or unroll the support unit, wherein the display unit and the support unit are rolled and unrolled together by the first driving means and the second driving means operating simultaneously, and wherein the support unit has a thickness such that its restoring force bending the support unit in one side direction is equal to a restoring force bending the display unit in another side direction when the display unit and the support unit are rolled out.