An anode active material with a high capacity capable of providing superior cycle characteristics and a battery using it are provided. An anode contains an anode active material capable of reacting with lithium. The anode active material contains at least tin, iron, and carbon as an element. The carbon content is from 11.9 wt % to 29.7 wt %, and the iron ratio to the total of tin and iron is from26.4 wt % to 48.5 wt %. Thereby, while a high capacity is maintained, the cycle characteristics are improved.