Provided is a 3D display device that simultaneously displays on a screen a main image of a 3D image and an added image which blocks a portion of the main image, and that is provided with the following: a display-region candidate determination unit that determines one candidate region from among a plurality of candidates for the display region, on the screen, for the additional image a depth agreement determination unit in which if it was assumed that the additional image is displayed in the candidate region determined by the display-region candidate determination unit, with respect to a difference in depth between the depth of the additional image and the depth of the main image displayed in a boundary region which is a region in the main image within a prescribed distance from a boundary line of the candidate region, determination is made as to whether such depth difference is within an allowable range determined in advance and an image synthesizing unit in which if it was determined that the depth difference found by the depth agreement determination unit is within the allowable range, the main image and the additional image are synthesized by superimposing the additional image onto the candidate region of the main image, and an image obtained as a result of the synthesis is displayed on the screen.La présente invention concerne un dispositif daffichage en 3D qui affiche simultanément sur un écran une image principale dune image en 3D et une image ajoutée qui bloque une partie de limage principale, et qui est doté : dune unité de détermination dune région daffichage candidate qui détermine une région candidate parmi une pluralité de candidates pour la région daffichage, sur lécran, pour limage supplémentaire dune unité de détermination daccord de profondeur dans laquelle sil a été supposé que limage supplémentaire est affichée dans la région candidate déterminée par lunité de détermination de la région daffichage candidate, relativement à une différence de profon
