Positive electrode for secondary battery, and secondary battery

This positive electrode for a secondary battery is provided with a positive electrode current collector and a positive electrode mixture layer disposed on the positive electrode current collector. The positive electrode mixture layer contains: a positive electrode active material containing a lithium transition metal composite oxide; and a carbon fiber having an outermost peripheral diameter of 20 nm or less, the lithium transition metal composite oxide contains 80 mol% or more of Ni relative to the total number of moles of metal elements other than Li, and an alkaline earth metal element is present on the particle surface of the oxide. The content of the carbon fibers is from 0.01% by mass to 1.0% by mass (inclusive) with respect to the total amount of the positive electrode active material. 二次电池用正极具备：正极集电体、和配置在前述正极集电体上的正极合剂层，前述正极合剂层含有：包含锂过渡金属复合氧化物的正极活性物质；和，最外周径为20nm以下的碳纤维，前述锂过渡金属复合氧化物含有相对于除Li之外的金属元素的总摩尔数为80摩尔％以上的Ni，在该氧化物的颗粒表面存在有碱土金属元素，前述碳纤维的含量相对于前述正极活性物质的总量为0.01质量％以上且1.0质量％以下。