A keyswitch device which is provided with a support mechanism which supports a keytop in a movable manner, and a membrane sheet which has a plurality of upper electrodes and a plurality of lower electrodes which respectively correspond to the plurality of the upper electrodes and which form contact pairs with the corresponding upper electrodes. A plurality of contact pairs are arranged for a single keytop. The rubber cup pushes the plurality of contact pairs which are arranged for the single keytop.