[Object] Provided is a means for improving cycle characteristics by suppressing electrode deterioration resulting from non-uniformity of voltage across an electrode plane in a high-capacity and large-area non-aqueous electrolyte secondary battery that includes lithium nickel-based composite oxide as a positive electrode active substance. [Solving Means] Disclosed is a positive electrode for a non-aqueous electrolyte secondary battery used in a non-aqueous electrolyte secondary battery in which the ratio value of battery area (projected area of the battery including the battery outer casing body) to rated capacity is 5 cm 2 /Ah or more and the rated capacity is 3 Ah or more, the positive electrode comprising a positive electrode current collector and a positive electrode active substance layer that is formed on a surface of the positive electrode current collector and has a positive electrode active substance containing a lithium nickel-based composite oxide and a spinel type lithium manganese composite oxide, in which, when the average secondary particle diameter (D50) of the lithium nickel-based composite oxide is D50 (A) [µm], the content ratio of the lithium nickel-based composite oxide in the positive electrode active substance layer is A [% by mass], the average secondary particle diameter (D50) of the spinel type lithium manganese composite oxide is D50(B) [µm], and the content ratio of the spinel type lithium manganese composite oxide in the positive electrode active substance layer is B [% by mass], the positive electrode satisfies the following Mathematical Formula 1 and Mathematical Formula 2: 0.5 ‰¤ D �¢ 50 A / D �¢ 50 B ‰¤ 2.0 B / A + B ‰¥ 0.2