A cathode material which does not easily deteriorate when used in batteries, a method for producing cathode materials, a cathode, and a lithium ion battery are provided. A cathode material including a cathode active material, in which the cathode active material is expressed by Li1+xAyDzPO4 (here, A represents one or more metal elements selected from the group consisting of Co, Mn, Ni, Fe, Cu, and Cr, D represents one or more metal elements selected from the group consisting of Mg, Ca, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, Ge, Sc, Y, and rare earth elements, 0