An indicator is useful for detecting pressure points on a denture. The indicator is made of a composition that easily adheres to oral mucosa, has a proper viscosity in an oral cavity environment, can be properly spread between an oral mucosa surface and a denture base, and easily specifies an affected part. The composition includes a fatty acid ester having a melting point of 30 to 50° C., a water-soluble high polymer, and a metal oxide. Preferably, the fatty acid is 40 to 95% by weight of the composition, the water-soluble high polymer is 1 to 59% by weight of the composition, and the metal oxide is 0.1 to 50% by weight of the composition.