Method for producing a cathode material for a lithium ion secondary battery

PROBLEM TO BE SOLVED: To provide: a positive electrode material for a lithium ion secondary battery, reduced in an amount of magnetic impurities and an amount of water-containing impurities; a positive electrode for a lithium ion secondary battery; and a lithium ion secondary battery.SOLUTION: A positive electrode material for a lithium ion secondary battery of the present invention includes: a center particle comprising LiFeMnMPO(where, 0.05≤x≤1.0 and 0≤y≤0.14 are satisfied, and M represents at least one selected from among Mg, Ca, Co, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, G and a rare earth element); and a carbonaceous coat coating the surface of the center particle. The positive electrode material has an amount of relative magnetization of 0.70 emu/g or less, and has a moisture content of 8,000 ppm or less, the moisture content being detected in a temperature range of from 100°C or above to 250°C or below by the Karl Fisher titration method.SELECTED DRAWING: None