A display device configured to display a first stereoscopic image and a second stereoscopic image different to the first stereoscopic image, according to an image source signal, the display device comprising: a display unit including a first group pixel including pixels emitting light in an even-numbered frame of the display device and a second group pixel including pixels emitting light in an odd-numbered frame of the display device; and an image processor adapted to: determine, from the image source signal, a first left-eye image signal and a first right-eye image signal for the first stereoscopic image, and a second left-eye image signal and a second right-eye image signal for the second stereoscopic image and divide each into an image signal respectively displayed in the first group pixel and the second group pixel, and form a basic alignment corresponding to a unit display period by arranging the image signals for each frame unit of the display device according to a display sequence, such that the unit display period is a period during which the first stereoscopic image and the second stereoscopic image are time-divided and displayed sequentially in the first group pixel and the second group pixel; wherein a driving frequency of the image source signal is different from a driving frequency of the display device such that there is a remaining period (PR_1), which is a period remaining after dividing the frame unit of the image source signal by an integer multiple of the unit display period (PB_1, PB_2), and the image processor is further adapted to alternately select the first stereoscopic image or the second stereoscopic image to be displayed during the remaining period (PR_1); and add an image source signal alignment corresponding to the remaining period to an image source signal alignment of a period corresponding to the integer multiple of the unit display period. a display unit including a first group pixel including pixels emitting light in an even-numbered frame of the display device and a second group pixel including pixels emitting light in an odd-numbered frame of the display device; and an image processor adapted to: determine, from the image source signal, a first left-eye image signal and a first right-eye image signal for the first stereoscopic image, and a second left-eye image signal and a second right-eye image signal for the second stereoscopic image and divide each into an image signal respectively displayed in the first group pixel and the second group pixel, and form a basic alignment corresponding to a unit display period by arranging the image signals for each frame unit of the display device according to a display sequence, such that the unit display period is a period during which the first stereoscopic image and the second stereoscopic image are time-divided and displayed sequentially in the first group pixel and the second group pixel; wherein a driving frequency of the image source signal is different from a driving frequency of the display device such that there is a remaining period (PR_1), which is a period remaining after dividing the frame unit of the image source signal by an integer multiple of the unit display period (PB_1, PB_2), and the image processor is further adapted to alternately select the first stereoscopic image or the second stereoscopic image to be displayed during the remaining period (PR_1); and add an image source signal alignment corresponding to the remaining period to an image source signal alignment of a period corresponding to the integer multiple of the unit display period. determine, from the image source signal, a first left-eye image signal and a first right-eye image signal for the first stereoscopic image, and a second left-eye image signal and a second right-eye image signal for the second stereoscopic image and divide each into an image signal respectively displayed in the first group pixel and the second group pixel, and form a basic alignment corresponding to a unit display period by arranging the image signals for each frame unit of the display device according to a display sequence, such that the unit display period is a period during which the first stereoscopic image and the second stereoscopic image are time-divided and displayed sequentially in the first group pixel and the second group pixel; wherein a driving frequency of the image source signal is different from a driving frequency of the display device such that there is a remaining period (PR_1), which is a period remaining after dividing the frame unit of the image source signal by an integer multiple of the unit display period (PB_1, PB_2), and the image processor is further adapted to alternately select the first stereoscopic image or the second stereoscopic image to be displayed during the remaining period (PR_1); and add an image source signal alignment corresponding to the remaining period to an image source signal alignment of a period corresponding to the integer multiple of the unit display period.