1. An X-ray topographic method for minding a boundary between a dislocation-appearing area and a dislocation-disappearing area in an unprocessed single crystal ingot as it is after being produced by Czochralski method, comprising the steps of: (a) supporting the unprocessed single crystal ingot rotatably on its axis and movably along its axis; (b) irradiating X-rays to a peripheral surface of the ingot through an incident slit having a long and narrow opening, and obtaining an image of diffracted X-rays from the ingot with an X-ray television camera, followed by setting positional relationship between the ingot and an X-ray optical system so that an optimum image could be obtained; (c) disposing a two-dimensional X-ray recording medium at a position where the diffracted X-rays can be detected; (d) irradiating X-rays to the peripheral surface of the ingot through the incident slit, and scanning the ingot synchronously with the X-ray recording medium in an axial direction of the ingot while recording diffracted X-rays from the ingot; and (e) finding a boundary between a dislocation-appearing area and a dislocation-disappearing area by observing a topographic image recorded on the X-ray recording medium.