The X-ray CT apparatus includes an X-ray tube, a high-voltage power supply, an X-ray detector and a processing circuitry. The processing circuitry reconstructs, as a first image, any of a monochromatic X-ray image and a polychromatic X-ray image on a basis of pre-reconstruction data acquired by scanning an object, the polychromatic X-ray image being taken in a first X-ray energy band. The processing circuitry reconstructs, as a second image, a polychromatic X-ray image taken in a second X-ray energy band wider than the first X-ray energy band on a basis of a pre-reconstruction data acquired by scanning the object. The processing circuitry identifies an area of a correction target in the first image as a correction area. The processing circuitry corrects the correction area in the second image on a basis of the first image.