Used is a battery a battery (100) including: a battery terminal (106); a circuit (108) being electrically connected with the battery terminal (106); and a resonance frequency adjusting section (110) being directly connected or capacitively-coupled with the circuit (108), and being electrically connected with the battery terminal (106) not via the circuit (108). This makes it possible to provide a battery which does not require electrical connection except via a battery terminal for connection with an apparatus on which the battery is mounted, and which battery is unlikely to deteriorate an antenna characteristic.