For persons with severe disabilities who find it difficult to operate the joystick or the chin stick of an electric wheelchair, we have developed an interface that allows the wheelchair to be operated by gestures such as head movements. By using a camera to perform visual sensing, we aim to implement a non-contact non-constraining interface where no wires or equipment of any kind have to be attached to the user, thereby making the interface much more convenient to use. Range information obtained from a stereo camera is used to control the electric wheelchair in any situation regardless of whether it is used indoors or outdoors. We are keeping this study user-oriented by performing clinical trials with the help of actual users to determine where the camera should be situated, how it should be used, and so on.