  In order to identify the Higgs sector using future precision data, we
calculate the partial decay widths of the discovered Higgs boson with the mass
of 125 GeV into fermion pairs and gauge-boson pairs with one-loop electroweak
and one-loop QCD corrections in various extended Higgs models, such as the
Higgs singlet model and four types of two Higgs doublet models. In the
tree-level analysis, the patterns of deviations from the standard model
predictions in the partial decay widths for various decay modes are distinctive
for each model, due to the mixing of the Higgs boson with other neutral
scalars. Our present analysis shows that even with a full set of radiative
corrections we can discriminate these extended Higgs models via the partial
decay widths as long as any of the deviations is detected at future precision
measurements. Furthermore, we quantitatively show that in each model the
magnitude of the deviations can provide important information on the mass scale
of extra Higgs bosons under the theoretical constraints from perturbative
unitary and vacuum stability, which can be obtained without discovery of the
additional Higgs bosons.
