A battery with the high capacity, the superior cycle characteristics, and the superior initial charge and discharge efficiency, and an anode active material used for it are provided. The anode active material contains at least tin, cobalt, carbon, and phosphorus as an element. A carbon content is from 9.9 wt % to 29.7 wt %, a phosphorus content is from 0.1 wt % to 2.2 wt %, and a cobalt ration to the total of the tin and the cobalt is from 24 wt % to 70 wt %.