Skin problems caused by cosmetics include not only irritant and allergic contact dermatitis, but also leukoderma caused by application of active brightening materials and immediate type wheat allergy due to hydrolyzed wheat protein. These skin problems have characteristic clinical symptoms and causative components and require specific testing methods. This article describes the skin problems caused by cosmetics for each site where symptoms are induced. On the scalp and face, allergic contact dermatitis is induced by ingredients present in cosmetics and daily hygiene products and hair coloring agents, especially preservatives such as isothiazolinones. Allergic contact dermatitis on the face also occurs due to chemicals used in eyelash extensions and components in lipstick. In Japan, the number of cases of leukoderma caused by ingredients contained in whitening cosmetics has rapidly increased and has become a social problem. Skin problems caused by cosmetics involve not only delayed allergic reactions but also immediate type reactions. After sensitization of the skin to the protein component contained in cosmetics, ingestion of foods containing the protein induces immediate type allergy. We have already experienced about the case of anaphylactic shock induced in immediate type allergy by hydrolyzed wheat protein or cochineal. The most useful test for identifying allergic contact dermatitis is the patch test. Repeated open application test (ROAT) using the cosmetic product is also a useful skin test. Additionally, the skin prick test is performed for immediate allergy. The Skin Safety Case Information Network (SSCI-Net) was established to quickly collect cases of contact dermatitis caused by cosmetics and daily use products, and to share the information with organizations such as cosmetic companies, relevant government agencies, and academia. It is hoped that skin troubles caused by cosmetics will be minimized through the efforts of the SSCI-Net.