Positive electrode active material and non-aqueous elecrolyte cell

A positive electrode active material (4) and a non-aqueous electrolyte cell (1) which uses the positive electrode active material. The cell has a high discharge voltage without lowering the capacity and superior charging/discharging characteristics. To this end, the positive electrode active material contains a compound represented by the general formula Li x Mn y Fe 1-y PO 4, wherein 0