The increasing use of computed tomography (CT) as a diagnostic tool creates the need for an efficient means of evaluating the performance of the CT systems now in use. Usually the metal products have the defects during manufacturing and are inevitable. In the NDT system, ability for evaluate the casting defects such as cracks and pores is also very important. In the present study, several phantoms were made for evaluating CT system and defect analysis tools. The phantoms were CT scanned, and the result of CT scan was discussed. For the accuracy matters, measurements were made and compared with real objects. It is expected that phantoms used in the present study help to validate defect detection softwares.