  We calculate the next-to-leading order (NLO) electroweak (EW) corrections to
decay rates of charged Higgs bosons for various decay modes in the four types
of two Higgs doublet models (THDMs) with the softly broken discrete Z_2
symmetry. Decay branching ratios of charged Higgs bosons are evaluated
including NLO EW corrections, as well as QCD corrections up to
next-to-next-to-leading order (NNLO). We comprehensively study impacts of the
NLO EW corrections to the branching ratios in nearly alignment scenarios where
the couplings constants of the Higgs boson with the mass of 125 GeV are close
to those predicted in the standard model. Furthermore, in the nearly alignment
scenario, we discuss whether or not the four types of THDMs can be
distinguished via the decays of charged Higgs bosons. We find that
characteristic predictions of charged Higgs branching ratios can be obtained
for all types of the THDMs, by which each type of the THDMs are separated, and
information on the internal parameters of the THDMs can be extracted from the
magnitudes of the various decay branching ratios.
