To provide an auto white balance apparatus capable of performing stable white balance adjustment. Spatial frequency processes are administered on a tomographic image, with the frequency processing properties in the scanning direction of a measuring light beam set to be lower than the frequency processing properties in the direction of the optical axis of the measuring light beam. The orientation of the endoprosthetic parts relative to this characteristic direction is then determined. During the period of motion, a high-force can be applied to overcome friction and other adverse affects. The headrest has wings which extend outward from the side of the headrest to increase the size of the headrest. When an object in current touch information does not match an object in previous touch information stored in the memory unit 16, the tactile sensation providing unit 12 provides a first tactile sensation.