A flexible organic light emitting display (OLED) device includes a flexible substrate having a display area, a non-display area at a periphery of the display area and a folding region; at least one organic emitting diode on the flexible substrate in the display area; an encapsulation film covering the organic emitting diode; and a dam on the flexible substrate. The dam laterally surrounds the display area and includes: a first dam in the folding region; and a second dam outside the folding region, wherein the average thickness of the first dam is smaller than the average thickness of the second dam.