1. A medical image display system having a function of preparing three-dimensional image data on a subject including a plurality of luminal organs and displaying the prepared three-dimensional image data on a display apparatus as a three-dimensional image, the system being characterized by comprising: curved-surface setting means for specifying a desired luminal organ in an image showing the plurality of luminal organs displayed on the display apparatus and setting a curved surface where the specified desired luminal organ is present; image creation means for extracting, from the three-dimensional image data, pixel values on the curved surface set by the curved-surface setting means, creating curved-surface image data by use of the extracted pixel values on the curved surface, and reconstructing two-dimensional image data from the created curved-surface image data; and display control means for controlling the display apparatus so as to display the two-dimensional image data reconstructed by the image creation means.