A display device including a bendable display panel, and an operation method thereof. The display device includes a display panel including a flexible substrate and a display unit and a bending adjusting member fixed to a rear surface of the display panel, and changeable between a flat state and a bending state by external force. The bending adjusting member is bent in a width direction to form a curvature, has elasticity in the width direction and a longitudinal direction, and is maintained in any one state between the flat state and the bending state under a condition of non-application of external force.