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.