To provide a radiation CT apparatus that can reliably give a tomogram free from deviation of the center axis by one scan and simple operation.

A radiation CT apparatus, in initially performing reconfiguration arithmetic operation of radiation projection data collected by CT scanning by a reconfiguration arithmetic operation unit, uses preset provisional coordinates as projection coordinates of the rotation center axis, architects a tomogram along a prescribed slice face, displays a screen for altering the rotation axis coordinates including that tomogram and the provisional coordinates, shifts the projection coordinates of the rotation center axis in any desired direction to any desired extent by manipulation on that screen, causes the reconfiguration arithmetic operation unit to execute again the reconfiguration arithmetic operation, and thereby enables a clearer tomogram to be obtained by the reconfiguration arithmetic operation using the projection coordinates of the rotation center axis free from deviation of the center axis.