Among numerous factors that have an effect on the controllability for the use of mobile phones, the effects of product size and control location were investigated to find the form factors which most affect customer preference while controlling the mobile phones. Moreover we made an effort to find an improvement of preference according to control location. An experiment was conducted, in which preference scores were measured. It was found that the effect of product width was larger than that of thickness. The optimal control location was almost the same regardless of the hand length. The contour plot was derived by supported vector machine(SVM). The difference in sensitivity was found between the horizontal transfer and the vertical transfer of control location. The preferable control area was suggested by the contour plot and sensitivity analysis. The results of the study would be valuable to suggest the guidelines of control layout and packaging of mobile phones.