Nanoparticles composed of Eu-complex and polyimide were successfully fabricated through an improved reprecipitation method, followed by a chemical imidization. In this process, the excess addition of triethylamine, which inhibits acid decomposition of Eu-complex, provided intense luminescent nanoparticles. These nanoparticles showed intense red luminescence assigned to Eu3+, which showed broader peaks compared with an Eu-complex powder and peak shifts. These results imply that Eu-complex molecules were dispersed in the PI matrix homogeneously and strongly affected by the matrix. Moreover, composition with polyimide improved UV resistance of Eu-complex.