A dome switch device enables electric contact by pressing of a central region or even any other region of a dome sheet formed to extend in a longitudinal direction with the same result regarding the amount of electrical contact. The dome switch device preferably includes a dome sheet extending along a longitudinal direction and having conductivity and a contact module provided on a substrate such that a plurality of both-pole (two-pole) contact portions are arranged alternately along the longitudinal direction of the dome sheet, in which the contact module, when being pressed regardless of where along the dome sheet is pressed, whether being pressed on a central region thereof or any other region other than the central region, electrically contacts the dome sheet with a high quality electrical contact.