1. An image playback device, comprising: a storage part in which a mix of a plurality of 2D images and a plurality of 3D images are stored, each of the 3D images is obtained by synthesizing a pair of parallax images; an image conversion part that synthesizes a pair of parallax images generated from one of said 2D images stored in said storage part and converts the pair of parallax images into one new 3D image; and an image output part that outputs said 3D image stored in said storage part and said new 3D image converted by said image conversion part.