A foot switch device for activating a dental or medical treatment apparatus is provided. The foot switch device is particularly suitable for controlling an ultrasonic dental scaler. The foot switch device includes a base plate; a central housing attached to the base plate; an upper, moveable cover mounted on the housing; and a connecting collar attached to the upper cover for retaining the cover on the housing while allowing the cover to move upwardly and downwardly relative to the housing. The central housing contains a first electrical switch for transmitting a first signal to the apparatus, and a second electrical switch for transmitting a second signal to the apparatus. An operator depresses the upper cover with his or her foot to activate the switching mechanism and control the operation of the dental or medical apparatus.