A negative electrode material and a battery which have an excellent cycle characteristic as well as a high capacity are provided. A positive electrode housed in an exterior can and a negative electrode housed in an exterior cup are laminated with a separator therebetween. An electrolytic solution of lithium salt dissolved in a solvent is poured into the inside of both the exterior can and the exterior cup. The negative electrode contains Mg.sub.2-xMII.sub.xMI. MI expresses a first element such as Si, Sn, Ge, Pb, or the like. MII expresses a second element which is a metallic element, preferably Mn, Cu, Zn, or the like except both Mg and the first element. X is preferably in the range of 0.1.ltoreq.x.ltoreq.1.9. Substituting part of Mg by the second element MII can produce the distortion of the crystal structure, ease distortion accompanying the occluding/releasing lithium, and improve the charge and discharge efficiency and the cycle characteristic.