A composite thin layer with three-layered structure of J-aggregate/aminothiol/sputtered-Ag-islands has been found to show remarkable enhanced fluorescence in the J-band, which is believed to be due to some large induced emission dipole in the Ag island film. For confirmation of this basic scheme and for better quantitative understanding of the enhanced fluorescence, the film extinction spectra were separated into real absorption and reflection and their individual correlations with the fluorescence yield were analyzed. The fluorescence enhancement needed considerably thick Ag island films, suggesting some critical roles of the island film morphology.