Keys that structure the keyboard have a diamond-shaped form that is symmetrical in both the vertical and the horizontal directions, disposed so that none of the edges of the surface in which the keyboard is formed are parallel with any of the edges of the diamond shapes. To each key is applied a marking in one or two orientations depending on the orientation of use of the mobile communications terminal. In the keyboard, these types of keys are laid out in a staggered pattern, wherein the markings are applied in positions that are on a straight line that passes through each of the keys in two rows of keys that are adjacent in the vertical direction on keys that are used when the mobile communications terminal is used in the horizontal orientation.