To provide an antenna system of which a size is reduced, and which is devised to achieve good communication.

The antenna system includes an antenna connected to a wireless transmission/reception circuit, and is provided with a feeding state detection means for detecting a feeding state of at least one of feeding parts out of respective feeding parts provided on a plurality of parts of the antenna, and a feeding part switching means for connecting either one of the feeding parts to the wireless transmission/reception circuit depending on a detection result of the feeding state detection means.