To provide a 
lithium / 
nickel / 
cobalt / 
manganese-containing 
composite oxide powder which has a 
high weight capacity density, a high packing property, an excellent cycle property, an excellent 
discharge rate property and an excellent safety, and which has little content of free alkalis and is free from gelation at a time of producing a 
slurry.A 
lithium / 
nickel / 
cobalt / 
manganese-containing 
composite oxide powder represented by the formula LipNixCoyMnzMqO2-aFa (wherein M is at least one element selected from the group consisting of Al, Ge, Sn, 
alkaline earth metal elements and 
transition metal elements other than Co, Mn and Ni, 0.9≦p≦1.1, 0.2≦x≦0.5, 0.2≦y≦0.5, 0.1≦z≦0.4, 0≦q≦0.05, 1.9≦2-a≦2.1, p+x+y+z+q=2, and 0≦a≦0.02), characterized in that when the 
powder is classified into 
small particle size-classified particles with an average particle size of 2 μm≦D50≦8 μm and 
large particle size-classified particles with an average particle size of 10 μm≦D50≦25 μm, the ratio of (% by weight of the 
small particle size-classified particles) / (% by weight of the 
large particle size-classified particles) is from 15 / 85 to 40 / 60, the 
molar ratio (ps) of 
lithium to the total of 
nickel, 
cobalt, 
manganese and the M element contained in the 
small particle size-classified particles is smaller than the 
molar ratio (pl) of lithium to the total of nickel, cobalt, manganese and the M element contained in the 
large particle size-classified particles.