An X-ray computed tomography apparatus according to the present embodiment comprises a gantry and a tube current setting circuitry. The tube current setting circuitry set tube currents for the respective imaging regions. To be specific, the tube current setting circuitry calculate X-ray absorption index values in the respective imaging regions, based on scanogram image data, determine tube current values corresponding to the X-ray absorption index values for the respective imaging regions, and correct the tube current values of the respective imaging regions except for a reference region based on a relative relationship between an X-ray absorption index value of the reference imaging region and tube current values of the other imaging regions.