A 2D/3D image conversion system includes target phase value calculating means for calculating a target phase value per parallax calculation region based on a dynamic range of a preset target phase value and depth information per given unit area generated by depth information generating means; real phase value calculating means which calculates a current real phase value per parallax calculation region in a manner to progressively approximate a real phase value to a target phase value of a parallax calculation region with a corresponding previous real phase value and then determines a current real phase value per given unit area based on the current real phase value per parallax calculation region thus obtained; and phase control means for producing a first image signal and a second image signal from a signal residing in each given unit area of the 2D input image, the first and second image signals having a horizontal phase difference therebetween based on the current real phase value corresponding to the given unit area.