An integrated machine tool is a type of multi-axes machine tools that has capabilities of both milling and turning. This paper presents a method to measure the dynamic angular motion accuracy of a rotation axis (B-axis) of a milling spindle under the synchronous motion by the B axis and linear axes. The present scheme identifies dynamic motion errors at the tool tip in radial and tangential directions by using the combination of ball bar measurements. The effect of setup errors is discussed in details. As case studies, the present scheme is applied to two different integrated machine tools, the one with a B-axis driven via a worm gear, and the other with a B-axis driven by a direct drive motor. The dynamic motion error is evaluated and its error sources are diagnosed on each machine.