Nonaqueous electrolyte secondary battery

The nonaqueous electrolyte secondary battery comprises: an electrode body in which a positive electrode and a negative electrode are wound in a flat shape with a separator interposed therebetween; and a nonaqueous electrolyte. The positive electrode has a positive electrode mixture layer containing a positive electrode active material. 0.10-0.30 mass% of ceramic particles are added to the positive electrode mixture layer, the volume-based median diameter (D50) of the ceramic particles is 0.5 [mu] m or less, the air permeability of the separator is 165-310 sec/100 ml, and the air permeability of the flat portion of the separator is 120-140% with respect to the air permeability of the curved portion of the separator. 非水电解质二次电池具有：正极与负极隔着分隔件卷绕成扁平状的电极体、和非水电解质，正极具有包含正极活性物质的正极复合材料层。正极复合材料层中添加有0.10～0.30质量％的陶瓷颗粒，陶瓷颗粒的体积基准的中值粒径(D50)为0.5μm以下，分隔件的透气度为165～310秒/100ml，分隔件的平坦部的透气度相对于分隔件的曲面部的透气度为120～140％。