To enhance the speed of scout view imaging of X-ray CT equipment, reduce the dose of an X-ray automatic exposure mechanism and to improve the image quality.

In the scout view imaging of this X-ray CT equipment, the speed enhancement of the scout view imaging is attained. The X-ray automatic exposure mechanism images a tomogram having an image quality uniform in the z-direction using projection data by a helical scout scan by an ultra-low dose helical scan performed in the scout view imaging for improving the accuracy of the X-ray automatic exposure mechanism, or projection data generated by a reprojection process in respective view directions in respective z-direction coordinate positions of a three-dimensional image by the tomogram obtained thereby and continuing in the z-direction. This X-ray CT equipment allows the X-ray automatic exposure mechanism to find an optimal X-ray tube current in each view in each z-directional coordinate position and images the tomogram with the optimal image quality under the optimal and reduced-dose imaging condition.