© 2014 Fuji Technology Press. All rights reserved. This paper proposes a method of simulating the effects of the machining center motion errors onto the finished surface. The proposed simulation method consists of the servo delay models of feed drive systems, a geometrical error model of the machine tool, a machined shape simulator, and a renderer. In order to compare the simulated finished surfaces with the machined one, tests consisting of machining spheres are carried out using a ball-end mill. As result, it is proven that the proposed simulation method can adequately simulate the effects of motion errors on the finished surface. In addition, an investigation into the cause of blemishes is carried out. It is also confirmed that the proposed method can be an effective tool in the identification of the causes of blemishes on the surface.