A key input device includes: keys each including a contact portion provided on its back surface; a holder holding the keys movably; a conductive member opposed to the holder; and a circuit board having a switch surface and switches arranged on the switch surface and each contactable with the contact portion of a corresponding key. The conductive member is interposed between the switch surface and the holder. The holder has first through holes, and the conductive member has second through holes. At least one of the contact portion and the switch is inserted in a corresponding one of the first through holes, and at least one of the contact portion and the switch is inserted in a corresponding one of the second through holes.