In this study, I invastigate about oriental medical drug, dosage form and directions in external therapy of contact dermatitis. and after study on relationship oriental medical drug, dosage form and directions with cause, symptom and differentiation of symptom and sign. The results are as follows; 1. Most frequently used oriental medical drug is until qing(淸) dynasty Eriocheir sinensis H. Milne-Edwards(蟹), Salix babylonica L.(柳葉), Natrii sulfas(芒硝), Allium macrostemon Bge.(해), Nelumbo nucifera Gaertn.(荷葉), nowadays in Korea and China Phellodendron amurense Rupr.(黃柏), Gypsum(石膏), Rheum palmatum L.(大黃), Baphicacanthus cusia Bremek(靑黛), Talcum(滑石). 2. In the frequency of dosage form, until qing(淸) dynasty powder 1case, liquor 49cases, liquer and solid mixture 58cases, nowadays Korea and China powder 16cases, liquor 96cases, liquer and solid mixture 59cases. 3. Most frequently used directions of dosage is thinly attaching method(薄貼法), attaching method(敷貼法), furnigating and cleansing method(熏洗法), cleansing method(洗傷法), wet dressing method(濕敷法), spreading powder method(撲粉法), plaster method(途차法), rubbing skin method(摩擦法) 4. In the external therapy of contact dermatitis, oriental medical drug's usage is based on stage of contact dermatitis In acute stage, most frequently used drug is heat and damp remove drug(淸熱燥濕藥), nature of drug(藥性) is bitter taste and cold charactor(苦寒), In chronic stage, most frequently used drug is nourishing the blood drug(養血藥), promoting blood circulation drug(活血藥). 5. The dosage form of drug is based on symptom. In acute stage, when papules and vesicles, or erosion and exudation is the main symptom of skin, liquor or powder is used, when erosion and crust is the main symptom of skin, plaster is used. In chronic stage, plaster is used. 6. In the directions of dosage is based on dosage form of drug and symptom. In acute stage, when papules and vesicles is the main symptom of skin, fumigating and cleansing method, cleansing method, plaster method is used, when erosion, vesicles and exudation the main symptom of skill, cleansing method, wet dressing method, spreading powder method, attaching method, spreading powder method is used, when crust is the main symptom of skin, plaster method is used. In chronic stage, plaster method, rubbing skin method is used.