This paper presents a surgical robot mechanism optimization method considering of the working error and operator’s muscle burden. The virtual surgical system was developed to simulate the visual and haptic feedback. The participants operated the VR surgical simulation system while the authors measured the working error and the participant’s joint motion. The histogram was made of the data to show the distribution. The authors estimated the appropriate probabilistic distribution model using Akaike's Information Criterion (AIC) method. As a result, there were many cases most applicable to the Weibull model.