In order to provide an X-ray CT apparatus including a rotating portion capable of enduring a high speed rotation and tilting, the rotating portion includes a cylinder portion 42, a ring portion 41 that is disposed at a position which is offset from the center in the direction of a rotation axis 32 of the cylinder portion 42, and the cylinder portion 42 and the ring portion 41 are supported by spoke portions 43 to 46. An X-ray tube and one or more circuit units are fixed on the inner wall of the cylinder portion 42. Thereby, the centers of gravity of an X-ray detection unit and the circuit units can be positioned at the center position in the direction of the rotation axis 32 of the cylinder portion 42. Since the centrifugal force of the X-ray detection unit or the like can be supported in the vicinity of the center in the direction of the axis 32 of the cylinder portion 42, distortion of the cylinder portion 42 is not easily generated, and the rotating portion capable of enduring the high speed rotation or the tilting can be provided.
