Provided are a method and apparatus for displaying a two-dimensional (2D)/three-dimensional (3D) image, and apparatus to execute the same, the method including determining whether an input image sequence having a first frame rate is a 2D image sequence or a 3D image sequence, wherein, if the input image sequence is a 2D image sequence, generating a 2D output image sequence having a second frame rate, the 2D output image sequence including the input image sequence and a 2D intermediate image generated from the input image sequence, and wherein, if the input image sequence is a 3D image sequence, generating a 3D output image sequence having a third frame rate, where a left-viewpoint intermediate image, a right-viewpoint intermediate image and the input image sequence are repeatedly included in the 3D output image sequence, the left-viewpoint intermediate image is determined from at least one left-viewpoint image in a left-viewpoint image sequence included in the input image sequence, and the right-viewpoint intermediate image is determined from at least one right-viewpoint image in a right-viewpoint image sequence included in the input image sequence.