According to one embodiment, an X-ray CT apparatus includes a fixed part, a rotating part, a detector, an A/D converter, a data transmitter, and a wireless transceiver. The rotating part is configured to be rotatably attached to the fixed part to rotate around a subject. The detector is arranged in the rotating part, and detects X-rays emitted from an irradiator and generates an analog signal. The A/D converter is arranged in the rotating part, and converts the analog signal to a digital signal. The data transmitter is arranged in the rotating part, and, upon receipt of the digital signal from the A/D converter, transmits the digital signal to a data receiver arranged in the fixed part. The wireless transceiver wirelessly transmits and receives signals in at least a part between the detector and the A/D converter or between the A/D converter and the data transmitter.