To provide an extremely economical cap using photocatalysis, and capable of easily providing the effects of preventing depilation of the hair and promoting growth of the hair while daily living the usual life.

This cap is obtained by forming pure titanium having titanium oxide thin film having photocatalysis and formed on the surface, into a mesh shape, and further forming the mesh-shaped titanium into a cap shape capable of covering the scalp. The cap using the photocatalysis is worn in sunshine or in an artificial light such as the one of a fluorescent lamp.