A method of manufacturing a nonaqueous secondary battery includes: constructing a battery assembly with a positive electrode, a negative electrode, and a nonaqueous electrolytic solution, the nonaqueous electrolytic solution containing an unsaturated carbonate; activating the battery assembly to decompose a portion of the unsaturated carbonate such that a percentage of the unsaturated carbonate is adjusted to be 0.9 mass % or less with respect to 100 mass % of a total amount of the nonaqueous electrolytic solution; self-discharging the battery assembly to measure a voltage drop amount; and determining whether internal short-circuit occurs in the battery assembly based on the voltage drop amount.