Separator for non-aqueous secondary battery and non-aqueous secondary battery

A separator for a non-aqueous secondary battery, the separator comprising:

• a porous substrate including a polyolefin microporous film;
• and
• a porous layer that is provided on only one side of the porous substrate, and that contains a resin having at least one bonding group selected from the group consisting of an amide bond, an imide bond, and a sulfonyl bond,
• wherein, in the porous substrate, an absolute value of a difference between a temperature of an endothermic peak observed at from 120° C. to 145° C. in a temperature raising process 1, and a temperature of an endothermic peak observed at from 120° C. to 145° C. in a temperature raising process 2, is 1.50° C. or higher in differential scanning calorimetry (DSC) measurement when the temperature raising process 1 of continuously raising the temperature from 30° C. to 200° C. at a temperature change rate of 5° C./min in a nitrogen atmosphere, and the temperature raising process 2 of lowering the temperature from 200° C. to 30° C. and raising the temperature from 30° C. to 200° C., are performed.