PROBLEM TO BE SOLVED: To provide a SPECT image reconstruction apparatus capable of properly performing an attenuation correction using a X ray CT image.SOLUTION: The SPECT image reconstruction apparatus obtains a SPECT imaging image and a X ray CT image from a patient (P1). When a CT value of the X ray CT image is converted into a linear attenuation coefficient so as to generate an attenuation coefficient map, its conversion ratio is changed to generate a plurality of attenuation coefficient maps (P2), and the imaged image is subjected to attenuation correction using a plurality of generated attenuation coefficient maps (P3), and a plurality of attenuation correction images is reconstructed (P4). Next, the plurality of attenuation correct images (P4) and control data (P5) are compared on a polar map (P6), and the attenuation correction image of the patient whose alienating part size becomes the maximum is obtained and outputted as an optimum attenuation correction image (P7).
