To obtain a composition for external use not only excellent in properties of the retention of pharmaceutically effective components in the hair and skin, but also being light and hardly causing the break of a container, excellent in treatability, and further capable of suppressing the absorption or the like of the pharmaceutically effective components, and good in preservation stability in the container.

This composition for external use contains (a) a high-molecular compound containing a unit represented by general formula (I) [wherein, R1 is a hydrogen atom or a methyl group; R2 is a 1-4C alkylene group; Y is O or NH; R3 and R4 are each a hydrogen atom or a 1-4C alkyl group], and (b) the pharmaceutically effective component such as 1-hydroxy-2-pyridone-based compound, and is characterized in that the composition is charged in the container having ≤1 g/mL ratio of the total weight of the container per volume. The composition preferably further contains an anionic surfactant.