The γ-ray spectrum produced from the thermal neutron capture on enriched gadolinium targets ( 155 Gd and 157 Gd) were measured using the ANNRI Germanium Spectrometer at J-PARC. We have also built a γ-ray emission model of 158 Gd decay, in which γ rays were classified into discrete prompt γ rays and continuum spectrum. We compared the data and our model, and found a fair agreement between them at the level of 26% over the γ-ray energy from 0.2 to 8.0 MeV. In this proceedings, the measured spectra and the model are described.