In a method for displaying a three-dimensional stereo image, a left-eye image defined by multiple left-eye strip pixels and a right-eye image defined by multiple right-eye strip pixels are displayed such that the left-eye pixels and the right-eye pixels are arranged alternately from the left to the right in a width direction. The left-eye image and the right-eye image are guided separately to the left eye and the right eye of an observer. Then, the left-eye image and the right-eye image are shifted by one pixel in an oscillating manner, and the left-eye image and the right-eye image are deflected synchronized with the one-pixel shifting operation.