To form a thin and strong decoration surface, in a nail decoration method (nail art) using a sealing material (nail decoration member) and a photocurable gel agent.

After forming a base layer 12 by applying a photopolymerization type gel agent to the surface of a nail B and curing it, a nail decoration member (sealing material A) formed into a thin film shape with the same material as a base layer forming gel agent on a surface in an uncured state (uncured gel 12a) and turned to a desired color and shape is stuck with an uncured base layer surface as an adhesive layer and cured.