To provide an X-ray CT apparatus capable of preventing serious errors from occurring in advance while enabling quicker response to errors or giving an alarm to an operator by always monitoring communication states in a rotating section and a fixed section of a gantry and dynamically setting an alert level.

The X-ray CT apparatus 1 includes the gantry 2 in which the rotating section 5 and the fixed section 6 are coupled to perform communication with each other by a slip ring. In the apparatus 1, a main control unit 31 monitors communication errors of the slip ring, and counts the number of communication errors generated in imaging. The main control unit 31 compares the number of errors per unit time in this imaging with a threshold value every time imaging is performed, and changes the alert level depending on the result of comparison. The control unit restricts the operation of the gantry 2 or performs alarm output, depending on the alert level.