The present invention is an antenna apparatus attached to an electronic device and includes an antenna section (11) having an antenna element (18) provided with two or more power supply points (19) and two or more earth points (20); and an earth point switch (21) which is provided correspondingly to each earth point (20) and connects or disconnects the earth point (20) from a ground. Selectively turning on or off the earth point switch (21) selects the earth point to adjust the resonance frequency.