In an X-ray CT apparatus including an X-ray area detector that has a matrix structure and is represented by a multi-array X-ray detector or a flat-panel X-ray detector, radiographic conditions (protocols) for imaging of each position represented by a z-coordinate are optimized in relation to an X-ray cone beam that spreads in a z direction. A slice thickness of a tomographic image is freely controlled in the z direction using a z filter during a conventional scan or a cine scan. For each tomographic image, a reconstruction function, an image filter, a scan field, a tomographic-image tilt angle, and a position of a tomographic image are freely adjusted or independently designated for scanning of each position in the z direction. Thus, a tomographic image is reconstructed. Moreover, the position of a beam formation X-ray filter in the z direction is shifted in order to optimize a patient dose that depends on the size of the scan field, and X-ray quality.