The multi-layer display device apparatus has a first display part, a second display part arranged at the rear-side of the first display part, a transforming part arranged between the first and the second display part. The transforming part transforms a linear polarized light in to a non-polarized light. Further, the display device has a storage part which stores a parameter for adjusting the image quality of the image displayed on the first and second display part, and an image adjustment part which adjusts the image quality of the image displayed in the first and second display part based on the parameter stored in the storage part.