In an X-ray CT apparatus 1 and an X-ray CT method, an image reconstruction unit uses, as projection data, a ratio Φ1/Φ2 between the number of transmitted X-rays within a predetermined energy range Φ1 that is smaller than the K-absorption edge of an object to be inspected, and the number of transmitted X-rays within a predetermined energy range Φ2 that is greater than the K-absorption edge of said object to the inspected, performs convolution of said projection of said projection data and a predetermined reconstruction function, and generates a CT image of said subject through back projection of the convolution result.
