A fingertip tactile sense input device for a personal digital assistant capable of various input operations produced by a moving fingertip over projections recognized by the fingertip tactile sense. An input plate has a plurality of fingertip input projections and input control means that encodes an input signal when a projection is depressed. A fingertip can be moved over the input plate with the wrists fixed. The projections are disposed within a surface area outlined by an inverted generally egg-shaped curve C1 or C2, which is usable equally by the index fingertip of either hand.