An X-ray CT apparatus of an embodiment includes an X-ray tube, an X-ray detector, a data processor, a battery, a rotating body, and processing circuitry. The X-ray detector is configured to detect X rays output from the X-ray tube. The data processor is configured to process a signal output from the X-ray detector. The battery is configured to supply electric power to the data processor. The rotating body is configured to rotatably support the X-ray tube and the X-ray detector, the X-ray tube facing the X-ray detector, and further to rotatably support the data processor and the battery. The processing circuitry is configured to monitor a remaining capacity of the battery, and determine a scanning condition on the basis of the remaining capacity.