A positive electrode active material for a battery, the positive electrode active material comprising a compound having a crystal structure of space group Fm-3m and represented by composition formula (1): LixMe1αMe2βO2 . . . (1). In the formula, Me1 represents one or more elements selected from the group consisting of Mn, Ni, Co, Fe, Al, Sn, Cu, Nb, Mo, Bi, Ti, V, Cr, Y, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, Ta, W, La, Ce, Pr, Sm, Eu, Dy, and Er, Me2 represents one or more elements selected from the group consisting of B, Si, and P, and the following conditions are met: 0