According to an aspect of the present invention, there is provided an X-ray CT scanner including: a gantry a revolving body provided inside the gantry an X-ray tube assembly provided in the revolving body a heat radiator provided inside the revolving body so as to be connected to the X-ray tube assembly a heat storage material provided in the heat radiator and capable of accumulating a heat generated by the X-ray tube assembly and an X-ray detector provided inside the revolving body so as to oppose the X-ray tube assembly.
