Resolving power of high spatial resolution X-ray computed tomography (CT) system was evaluated by taking CT images of artificial test patterns at BL47XU in SPring-8 (SP-μCT BL47XU). The system consists of an in-vacuum type undulator, a double crystal monochromator cooled with liquid nitrogen, a high precision sample stages and a high spatial resolution X-ray detector. For the precise measurement of the resolving power, the artificial test patterns of Cu/Al concentric multilayer were fabricated by DC sputtering deposition at AIST Kansai. 7 or 5 layers of Cu/Al are deposited by period of 2 μm and 1 μm. Therefore the resolving power could be measured at 4 μm and 2 μm with each test pattern. It was confirmed that the system had a resolving power of 2 μm at 15keV from the CT images of test patterns. The resolution is not independent on the used energy. At 30keV, the resolving power was slightly poorer than 2 μm. The result was consistent with the point spread functions of the high resolution detector measured by focused micro-beam.