The purpose of the present invention is to newly provide a method with which it is possible to appropriately evaluate the protective effect of a skin-external agent such as a sunburn-preventing cosmetic, particularly to evaluate how a UV-ray protective effect is affected by heat. This evaluation method is characterized by including (1) a step for forming a coating film of a skin-external agent on a substrate, (2) a step for heat-treating the coating film of the skin-external agent, and (3) a step for measuring the UV-ray protective effect of the heat-treated coating film of the skin-external agent. The heat treatment is preferably carried out for at least one minute at a temperature of 30-70 DEG C. The step for measuring the UV-ray protective effect preferably includes at least one selected from testing methods that involve comparing some kind of UV-ray protective effect with SPF measurement, UVAPF or PFA measurement, critical wavelength measurement, absorbance measurement, and transmittance measurement. This evaluation method can also be performed in vivo or in vitro.本發明之目的在於提供一種可適當地評價防曬化妝料等皮膚外用劑之防禦效果、特別是熱對紫外線防禦效果產生之影響的新穎方法。本發明之評價方法之特徵在於包含：(1)於基體上形成皮膚外用劑之塗膜之步驟、(2)加熱處理上述皮膚外用劑之塗膜之步驟、及(3)測定上述經加熱處理之皮膚外用劑之塗膜之紫外線防禦效果之步驟。並且，上述加熱處理較佳為於30℃～70℃之溫度下實施1分鐘以上。又，上述測定紫外線防禦效果之步驟較佳為包含選自SPF測定、UVAPF或PFA測定、臨界波長測定、吸光度測定及透過率測定、及某些比較紫外線防禦效果之試驗法之至少一種。又，本發明之評價方法可於活體內或活體外實施。
