A 3D image processing apparatus includes: a main screen image processing unit which generates a main screen processed image by performing a format conversion process on a main screen image; a sub screen image processing unit which generates a sub screen processed image by performing a format conversion process on a sub screen image; and a synthesizing unit which generates a synthesized image by synthesizing the main screen processed image and the sub screen processed image. Furthermore, the main screen image processing unit generates a left screen output image by performing the format conversion process on a left screen input image that is a left half of a 3D image, and the sub screen image processing unit generates a right screen output image by performing the format conversion process on a right screen input image that is a right half of a 3D image.