A flexible display device and method for detecting a bend on the device are discussed. The method includes detecting a first bend on the flexible display device and measuring a first degree of the first bend; recognizing the first bend as a first valid flex input when the measured first degree of bend surpasses a first error threshold value; and recognizing an end of the first valid flex input when the measured first degree of bend falls below a first release threshold value, wherein a maximum degree of bend measured during the first bend is recognized as a first peak value, wherein the first error threshold value is determined based on a degree before the flexible display device is bent and the first release threshold value is determined based on the first peak value, and wherein the first release threshold value is different from the first error threshold value.