An electronic fence system comprises a fence wire which radiates a radio signal for defining a boundary; a transmitter electrically connected to the fence wire and transmitting a boundary radio signal including a mode selection signal; and a receiver attached to the pet, that receives the boundary defining signal, and that generates either electrical shock only, or a combination of electrical shock and vibration as well as sound depending on the mode selection signal.If the pet has a hearing loss, or the circumference is noisy, a warning signal can be given through a touch to the skin of the pet. Since a vibration is applied first, and the shock follows it, no severe shock need be applied to the pet that will return into the confined area after having received a vibration. A pet's activity is restricted in a predetermined area.