The prompt fission γ-ray energy spectrum for cold-neutron induced fission of 235 U was measured in the energy range Eγ = 0.8-20 MeV, by gaining a factor of about 10 5 in statistics compared to the measurements performed so far. The spectrum exhibits local bump structures at Eγ ∼4 MeV and ∼6 MeV, and also a broad one at ∼15 MeV. In order to understand the origins of these bumps, the γ-ray spectra were calculated using a statistical Hauser-Feshbach model, taking into account the de-excitation of all the possible primary fission fragments. It is shown that the bump at ∼4 MeV is created by the transitions between the discrete levels in the fragments around 132 Sn, and the bump at ∼6 MeV mostly comes from the complementary light fragments. It is also indicated that a limited number of nuclides, which have high-spin states at low excitation energies, can contribute to the bump structure around Eγ ∼15 MeV, induced by the transition feeding into the low-lying high-spin states.