5-axis controlled machining centers with three linear axes and two rotary axes have been developed to produce mechanical parts and molds with complicated shape. Those machining centers are generally constructed at least by two links with rotational mechanism. The evaluation method of the deviations in the orthogonal three planes has been developed and already specified into the ISO standard. However, the evaluation method for five-axis controlled machining centers including A and C axes has not been investigated. In this study, the motion accuracy of the machining centers simultaneously controlled four axes is discussed. A ball-bar method is applied to the measurement of motion accuracy, and the simulation for evaluation of the error motion is conducted. The positional and geometric deviations existing in 5-axis controlled machining affect the simultaneous 4-axis control motion, and those deviations are estimated by the proposed method.