This paper describes the rationale used in the development of design guidelines for switch controls around the steering wheel in view of relating to the human operating characteristics. The resulting steering wheel control can be operated with ease and without a chance for any misuse. The results are based upon motion study, and relating to the surface area around the controls, where the thumb makes contact. First, a motion study was conducted, which involved recording the motion of the hand while operating the controls. Next, an experimental system was developed to measure the contact area and thumb pressure. A series of experiments was performed to evaluate operational areas, hand postures and thumb contact areas. The experimental results confirmed that the range of thumb movement in the upper location of the steering pad was bigger than the lower location, and the direction of contact area changes with control positions. Consequently, fundamental design guidelines for the layout of controls around the steering wheel were discussed by characteristics of thumb behavior.