Provided are a method for preparing a standard sample in which a uniform dispersion of a predetermined concentration of red phosphorus is guaranteed even in a very small amount, and an analytical method for quantitatively determining red phosphorus contained in a resin by pyrolysis-GC/MS, in which the standard sample is used. The method for producing a standard sample for quantitatively determining red phosphorus contained in a resin includes the steps of preparing a red-phosphorus-containing compound by weighing a predetermined amount of red phosphorus and uniformly mixing the red phosphorus in a resin; decreasing the number of particles having a maximum diameter of 5 μm or more to 1/20 or less of the number of particles having a maximum diameter of 1 μm or more and less than 5 μm by pulverizing the red-phosphorus-containing compound; and obtaining a standard sample by weighing about 0.05 to 10 mg, preferably about 0.1 to 0.5 mg of the pulverized red-phosphorus-containing compound. The analytical method is a method for quantitatively determining red phosphorus contained in a resin by pyrolysis-GC/MS, in which the standard sample is used.