Quantitative testing for formaldehyde in perfumery and cosmetics is required for sale and distribution in Japan, as formaldehyde is prohibited in those products due to its toxicity. The HPLC method and post-column derivatization with acetylacetone is a test method for formaldehyde in such cosmetics, introduced in the Methods of Analysis in Health Science (The Pharmaceutical Society of Japan, 2015). This article introduces examples of analysis of formaldehyde using a Shimadzu Nexera XR ultra high performance liquid chromatograph. The chromatogram of the standard solution showed a good peak shape, and the linearity of the calibration curve was also satisfactory. Actual samples of a shampoo, conditioner, and skin lotion were analyzed, and the results were below the minimum concentration of the calibration point specified in the cosmetic test method.