To find failure early or reduce the down time of an X-ray CT apparatus set in a hospital by monitoring the apparatus from a remote place.

Output data from an X-ray detector 303 at the time of X-ray irradiation, collected in the warm-up time of an X-ray tube when the X-ray CT apparatus is actuated almost everyday, are stored as maintenance data in a maintenance data storage device 310 in a maintenance computer 314 inside the X-ray CT apparatus or connected to the outside, and the result of monitoring on the presence of abnormality by a self-diagnostic program for remotely monitoring the X-ray CT apparatus or the maintenance data themselves are transmitted regularly to a service center from a communication device 312 via a communication network 313. The maintenance data comprise information on the state of a measuring system such as the X-ray tube 300, a collimator 302, a multi-channel type X-ray detector 303 and a data collection circuit 304, and therefore, if the maintenance data are monitored in a remote place, the premonition or the state of the trouble in the measuring system can be grasped there.