The perception models which explain perceived lengths of objects by static holding have two assumptions. One is strict rest of objects and the other is small fluctuation of them. In this paper, we measured the fluctuation of objects by using a 6 DOF (degrees of freedom) tracking system. It made clear firstly that the objects were certainly fluctuating. Secondly, the fluctuation was divided into the initial part just after the start of holding and the steady part after that. Thirdly, the fluctuation of the initial part was bigger than that of the steady part, but much smaller than that of wielded objects. We considered a muscle torque model, MTM, which consisted of a static moment and an inertia moment. The relation between angular acceleration and the coefficients of the MTM showed that subjects perceived lengths depending on dynamic characteristics of objects so much as angular acceleration increased.