  We calculate a full set of one-loop corrections to the Higgs boson coupling
constants as well as the electroweak parameters. We compute the decay rate of
the standard model (SM)-like Higgs boson ($h$) into diphoton. Renormalized
Higgs couplings with the weak gauge bosons $hVV$ ($V=W$ and $Z$) and the
trilinear coupling $hhh$ are also calculated at the one-loop level in the
on-shell scheme. Magnitudes of the deviations in these quantities are evaluated
in the parameter regions where the unitarity and vacuum stability bounds are
satisfied and the predicted W boson mass at the one-loop level is consistent
with the data. We find that there are strong correlations among deviations in
the Higgs boson couplings $h\gamma\gamma$, $hVV$ and $hhh$. For example, if the
event number of the $pp\to h\to\gamma\gamma$ channel deviates by +30% (-40%)
from the SM prediction, deviations in the one-loop corrected $hVV$ and $hhh$
vertices are predicted about -0.1% (-2%) and -10% $(+150%)$, respectively. The
model can be discriminated from the other models by measuring these coupling
constants accurately at future collider experiments.
