Abstract: In an X-ray diagnostic apparatus, there is additionally provided an aspect ratio conversion circuit in a video processor. A video signal derived from an X-ray TV camera for an R/F table system having an aspect ratio e.g., (1:1) is converted into a corresponding digital video signal. The digital video signal is alternately stored in two buffer memories in synchronism with a predetermined clock pulse, which accordingly may change the original aspect ratio (1:1) into a new one, i.e., (3:4). Then the video signal processed under the new aspect ratio is displayed on the monitor which has its own aspect ratio (3:4) different from the original aspect ratio of the TV camera.