A key switch device includes: an operation member to be depressed; a switch disposed below the operation member; a reaction force generating member that is provided between the operation member and the switch, performs elastic buckling deformation by depression of the operation member, gives a reaction force according to the elastic buckling deformation to the operation member; and a depression member that is provided between the operation member and the switch, and depresses the switch; wherein the reaction force generating member includes a supporter that supports the depression member.

A computer input device includes a button that is movable by an external force; an elastic unit that is positioned on a lower portion of the button, is deformed or compressed by the movement of the button, and provides an elastic force in response to the movement of the button; and a switch that is turned on or off by the movement of the button, wherein the button is movable in an on section, which is a section from an uppermost end position to a position where the switch is turned on, and an extra section, which is a section up to a position that is lower than the on section.