Summary One of the machine design, objectives is to maximize the functionality under the constraints of manufacturability. It is desirable for designers to be able to analyze the effect of geometrical errors due to manufacturing processes on the functional behavior of assemblies. We propose a method to evaluate the motion of an assembly of parts with geometrical errors. We make idealization of geometrical criers considering typical machining errors, and solve equations of motion of objects der the gravity and friction force from contact constraints by using Linear Programming Method. The result of calculation is useful for evaluating the effect of shape errors on the accuracy of the motion of assemblies.