According to one embodiment, an X-ray CT apparatus includes a gantry, a table on which an object is placed, a bed, and processing circuitry. The gantry is equipped with an X-ray source and an X-ray detector. The bed includes a moving mechanism which is configured to move the table in a horizontal direction and in a vertical direction. The processing circuitry performs a main scan and a prescan. The prescan is performed prior to the main scan. The processing circuitry calculates displacement of the table in the vertical direction and also calculates an angle of the table from the horizontal direction using data acquired in the prescan, and controls a position of the table and an angle of the gantry based on the displacement of the table and the angle of the table.
