Attenuation correction (AC) of myocardial perfusion stress-rest single photon emission computed tomography (SPECT) with hybrid SPECT/computed tomography (CT) is effective. But because CT scan is done two times, the radiation exposure of patients increases. Therefore, we suggested a new method of AC that can correct attenuation of SPECT images acquired during a rest examination by using the CT scan during a stress examination. AC was done using one CT scan and we evaluated the clinical appropriateness of using this method. Matters of this study were (1) positional reproducibility of data analysis machine (Xeleris) (2) phantom study: accuracy of registration by manual and repetition reproducibility (3) clinical study using ^99mTc-tetrofosmin. Comparison methods were analyzed by calculating the difference perfusion (Dp) with 17-segments model of American Heart Association and visual evaluation of three axis images in the myocardium. In the phantom study, because most of the score of 17-segments accord (Dp≤1), it was considered that the shift on SPECT/CT’s bed was reproduced by the shift on Xeleris. And it is shown that AC with CT scan on deference point was accuracy. In the clinical study, there were a few differences in Dp (Dp≤4) and approximately equal evaluation on visual evaluation was provided, which compared with conventional methods. Because AC of myocardial perfusion stress-rest SPECT by one CT scan showed that it was approximately equal in evaluation compared with conventional methods, we expect to be able to use this method in clinical cases.