A multiple-frequency antenna device includes an antenna unit and a frequency switch unit. The antenna unit includes an insulating substrate on which grounded first and second conductive layers are disposed. The first conductive layer is further connected to a radio-frequency (RF) circuit. The frequency switch unit is connected to the antenna unit in parallel, and includes a switching component, and a frequency adjustment: component connected to the antenna unit. The multiple-frequency antenna device is resonant at a first resonant frequency when the switching component is switched to a first state, and is resonant at a different, second resonant frequency when the switching component is switched to a second state.