A flexible display device may include a display unit, and a support mechanism. The support mechanism may include multiple supporting units arranged at intervals in a direction of a side edge of the display unit and fixed to a second surface, and a movable unit. The supporting units respectively define holes that have openings facing toward each other and communicating with each other. The movable unit passes through the holes and is movable relative to the supporting units. The shape is changed by adjusting a position relationship between the movable unit and the supporting units.