An electrode material comprising: surface-coated Li x A y D z PO 4 particles which comprise a carbonaceous coat on surfaces of the Li x A y D z PO 4 particles wherein A represents one or more selected from the group consisting of Co, Mn, Ni, Fe, Cu and Cr, D represents one or more 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<x ≤2, 0<y≤1, and 0<z≤1.5, characterized in that 80% or more of the surfaces of the Li x A y D z PO 4 particles are coated with the carbonaceous coat, the thickness of the carbonaceous coat is in a range of 0.1 nm to 20 nm, and an elution amount of Li is in a range of 200 ppm to 700 ppm and an elution amount of P is in a range of 500 ppm to 2000 ppm when the surface-coated Li x A y D z PO 4 particles are immersed in a sulfuric acid solution having a pH of 4 for 24 hours, wherein surface-coated Li x A y D z PO 4 particles are prepared by - spraying and drying a homogeneous slurry at a temperature in a range of 100°C to 300°C in order to obtain dried particles or granulated bodies, wherein the homogeneous slurry comprises an organic compound and an electrode active material precursor, - firing the resulting dried particles or granulated bodies in a non-oxidizing atmosphere at a temperature in a range of 650°C to 1100°C, and - thermally treating in a non-oxidizing atmosphere the resulting fired particles or granulated bodies at a temperature in a range of 40 to 500°C. surface-coated Li x A y D z PO 4 particles which comprise a carbonaceous coat on surfaces of the Li x A y D z PO 4 particles wherein A represents one or more selected from the group consisting of Co, Mn, Ni, Fe, Cu and Cr, D represents one or more 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<x ≤2, 0<y≤1, and 0<z≤1.5, characterized in that 80% or more of the surfaces of the Li x A y D z PO 4 particles are coated with the carbonaceous coat, the thickness of the carbonaceous coat is in a range of 0.1 nm to 20 nm, and an elution amount of Li is in a range of 200 ppm to 700 ppm and an elution amount of P is in a range of 500 ppm to 2000 ppm when the surface-coated Li x A y D z PO 4 particles are immersed in a sulfuric acid solution having a pH of 4 for 24 hours, wherein surface-coated Li x A y D z PO 4 particles are prepared by - spraying and drying a homogeneous slurry at a temperature in a range of 100°C to 300°C in order to obtain dried particles or granulated bodies, - spraying and drying a homogeneous slurry at a temperature in a range of 100°C to 300°C in order to obtain dried particles or granulated bodies, wherein the homogeneous slurry comprises an organic compound and an electrode active material precursor, - firing the resulting dried particles or granulated bodies in a non-oxidizing atmosphere at a temperature in a range of 650°C to 1100°C, and - thermally treating in a non-oxidizing atmosphere the resulting fired particles or granulated bodies at a temperature in a range of 40 to 500°C. - firing the resulting dried particles or granulated bodies in a non-oxidizing atmosphere at a temperature in a range of 650°C to 1100°C, and - thermally treating in a non-oxidizing atmosphere the resulting fired particles or granulated bodies at a temperature in a range of 40 to 500°C.