PROBLEM TO BE SOLVED: To provide an X-ray CT apparatus capable of easily associating a CT image with an image of a corresponding electrocardiographic waveform.SOLUTION: The X-ray CT apparatus according to one embodiment scans a subject with an X ray to acquire detection data. The X-ray CT apparatus includes a setup unit, an identification unit, a reconstruction processing unit, and a control unit. The setup unit sets a desired range to electrocardiographic waveform data of a subject acquired in parallel to the X-ray scan. The identification unit identifies a detection data item acquired at timing included in the desired range, in the detection data. The reconstruction processing unit reconstructs projection data based on the identified detection data and creates CT image data. On the basis of a signal of starting the reconstruction processing, the control unit stores electrocardiographic waveform image data based on the electrocardiographic waveform data in which the desired range is set and CT image data based on the identified detection data, with them being associated with each other.
