An image forming apparatus including first and second image forming portions, and a device for detecting a type of an image display medium, image formation by the first image forming portion being allowed when the medium type is a normal image display medium (PP), and image formation by the second image forming portion being allowed when the medium type is a reversible image display medium (TP). Another image forming apparatus including first and second image forming portions, and an image formation element setting switching device, image forming elements being set in a standard mode to a standard state for forming an image on a medium for the standard mode, and being switched in a non-standard mode to a non-standard state for forming an image on a medium for the non-standard mode.